[c22]

Why can't you slow down when driving past tall parked vehicles that you can't see through? If you are going slower you will have a chance to see them in advance, select a speed where your stopping distance is less than the length of the obstruction and be prepared to brake. You will have no chance of striking all but the most willfully suicidal of pedestrians.

Near my house there is an arterial I often cross where a large bush on the corner of the intersection obscures the view to the left from the stop sign roughly 10 feet back. I don't just stop at the sign then YOLO through the intersection, I stop, then creep forward, first looking for pedestrians or bicyclist that might step out from the bushes, then at the edge of bushes I stop again and look again both left and right for cars and bikes or pedestrians in the far lane before proceeding across. I often have to stop another time between the sign and the bushes for the pedestrian or bicyclist that just emerged, if I was focusing on getting across the arterial and beating cross traffic I would have killed every one of them.

[dpark]

At what speed do tall vehicles suddenly become transparent?

The idea that cars should drive past tall vehicles at 5 mph is slightly ridiculous. I have never ridden in a car with someone who constantly adjusted their driving speed based on the cars parked on the road. Choosing a reasonable speed? Of course. Extra care at obvious obstructions? Absolutely. Slowing traffic to 5mph because a van happens to be parked? No.

[c22]

It is not ridiculous if you are driving in a narrow lane close to the obstacles. When I am driving on a residential (one lane, parked cars on both sides) street and I am approaching a tall opaque van I start by noticing if anyone is around it as I approach, when I have better sight lines, then as I get near it I absolutely slow down from an average speed of 15-20mph to well under 10mph and yes, depending on the situation sometimes as low as 5mph or slower. When I am on a faster road with two or more lanes there is often room to move laterally in these situations and so my speed reduction is less extreme, but I absolutely do still slow down as I pass these vans/trucks, cover the brakes and also check my blind spot to see if there is room for evasive maneuvers should they be required. If I see people in the area as I approach and have reason to believe they might try to cross, enter or exit a car, or otherwise be near the lane of traffic I will often change lanes to the left if possible.