Driving - What age is more dangerous?

I think those statistics are probably misleading without a much deeper analysis...how often are they driving? how far do they drive? What time of day?
Even if the over 70s make up 10% of the driving population...most of them probably aren't going to work everyday, or may not drive every day, or not drive very far.
There's probably also a difference between the amount of driving they do at night as opposed to during the day.

Many older people stick to their own neighborhoods/shops/friends houses where they know the roads well.
My mother has a friend who is 95 and still drives (and even though she is mentally sound and still in good health, if I was one of her children...I would have stopped her by now) but, she never drives at night, or she drives to her daughter's house about 10mins away via the back streets and avoids main roads. She doesn't drive to the shops any longer, her children take her or they order her groceries to be delivered. So even though she'd be in the stats as a driver over 90...her actual driving is minimal and she only drives under fairly safe conditions, so the chances of her being in an accident are reasonably low.
Compare that to a 38yo woman who works and maybe has a child and the amount of time she spends driving around on main streets, or at night etc, then she's much more likely to be involved in an accident because there's more opportunity for one to happen.

I also think there's a huge difference between 70 and 90. I likely wouldn't think twice about getting in a car with a 70yo driver (unless they looked obviously unwell/unfit to drive), but definitely would a 90yo.

The physical driving test is what would be helpful to retake. My MIL had her license years after anyone giving her a test would have yanked it (and got in several accidents).

I think the road test is a much better gauge than the written test of a person’s abilities. Of course knowing the rules is important, but I think a person’s reaction time and the ability to see and hear what’s happening around them is much more important.

Texas requires you to go in person for a new photo and vision check at age 18 and then every 10 years. (I am fairly certain that's the number.) I have long thought you should have to do the written test then, too. Judging from how people drive around here, I don't think most people remember more than about 25% of the rules. I know that most of the time, those 25% cover what is needed, but for example, people flat out fail to yield to emergency vehicles and will almost rear end you when you pull over to do so. I really think that in an ideal world, you'd have to do at least a "lite" road test, too, but there's no way there will ever be enough people and time to do that.

Old people have shower reaction times and generally poorer vision (particularly at night) but also tend to drive slower and stick closer to home, so that lessens the risk somewhat.

Young people have better reactions and night vision but tend to drive faster and more often and are far more prone to driving under the influence.

True! Though I see all ages of people on their phones while driving, lots of 30 and 40 something looking people. Men in business suits are the worst and come on, I know your Audi has Bluetooth.

My 70+ mom and my late teen daughter both suck for different reasons. My daughter only drives with me once a month if that. My mother refuses to give a shit about her vision or reaction times and I don’t know how to get her off the road because she’s bad but not bad enough for legal intervention which seems insane.

Written tests certainly aren’t enough but how egregious does one have to be to not pass?

This. 

I fought with my Dad to get him to stop driving and it was exhausting.  I had to take his car away, you can imagine, how that went over.  I know he didn't want to give up his independence, I 100% get that, but nowadays there are so many other options to get around:  Uber/Lyft, shuttle bus at his assisted living, the dial-a-ride in our town. 

Even when his eye doctor said he was legally blind, he had macular degeneration so not totally blind, (I was sitting right next to him) he said he was fine to drive.  

I agree that the written test should be taken every decade or so.  The laws change all the time.  I've never had to re-take the written test and here are a a few things that have changed since I was 16:

• You have to have your lights on if it's rainy enough to have your wipers on
• You have to give a bicyclist 3 feet of space when passing them
• When making a turn, you can turn into any lane that is safe

I don't even know how many laws have passed/changed in the 45+ years since I started driving.

I am 100% for retaking a driving test periodically. It would be useful to do the written test as well because I truly believe some people have no idea what the laws are. For instance, if you are turning left or right and there are 2 turn lanes, you stay in your lane. You don't get to swing wide into the other lane. One of my biggest driving pet peeves.

I think younger drivers are more dangerous because they drive faster. The worst car wrecks around here tend to be drivers that are teens to early 20s. Often speeding. Often under the influence.

How can it not be a law in every state? If you are side x side with cars turning the same direction, they can swing into your lane? I would think that would cause lots of accidents.

Driver's Ed site RE turns

huskergal , here's a basic though incomplete summary. This is just addressing single lanes turning, not multiple lanes, I would assume you are legally correct if multiple lanes are turning. You are definitely logically correct. I missed that in your original post you were referring to multiple lanes turning, so you and I were looking at it differently. I was misreading the "swing wide into the other lane" part.

I do think the key thing is "if it is safe to do so." You can turn right on red (at least here in TX) IF IT IS SAFE TO DO SO and not contraindicated by any signage. So I can turn left into the far right lane, but only if it is safe to do so. In other words, I read it as if it isn't your given driving right, it is something you are allowed to do under certain conditions. (I mean, I guess everything is "if it is safe to do so," but if I have a green light and go through the intersection and get t-boned and it's as straighforward as that, the law would be on my side. If I turn left into the far lane and hit someone turning right into that lane, I'm guessing I would be on the hook.)