Rear back and rear side can be pretty dark, they changed recently for the driver/passenger side to make it tighter.
Although, manufactures aren't helping it with new cars coming with insanely dark rear sets of tints. Just like fog lights, manufacters only sell them because its cool (why else would it be in the advertising blurb... "with alloys and fog lights as standard")
Some manufacturers will actually tint beyond the UK legal requirements which is a bit daft really - there are some people who will trust that the manufacturer wouldn't provide something that isn't road legal (wonder if you could claim 'not fit for purpose'
Most new cars that are coming onto the market now seem to have "privacy tinted windows" fitted to the rear of the car. It's the "in" thing i guess.
It's when the front passenger and drivers side windows that are heavily tinted it gets worrying.
Many people with young kids like the idea that the kids can see out, have some protection from the sun on a hot day and can't be seen from outside.
Rear tints - arg - a pain in the backside for other people, as you can't see through them to see the road, as you can with "normal" windows. Even worse on people carriers and urban assault vehicles becuase they're so bloody high. At least we can look over the tops of cars.
Do you try and avoid following busses / transit vans etc? if you can't see enough then drop back a bit.
Not illegal though is it? If they still allow light to pass they're better than a van. So long as its driven responsibly and legally, what's the problem? Most of my initial driving was done in vans and I now primarily use side mirrors.
I too have done my fair share of driving large vehicles, in my case mini busses and learnt to drive them based on the door mirrors.
I also had a car that only had the internal mirror, so learnt to drive looking over my shoulder to change lanes.
most tints on car windows are legal and you can see more from inside than you can from outside, there is a legal limit to the tint fitted to windscreen and front windows.