Run a tank into a big mature oak tree at 30mph dead-centre, and while the tree and the tank may suffer mostly superficial looking damage, the personnel in the tank may in some respects come of worst vs. people in a good modern car hitting the same tree at 30mph.
This is because the people in the car will have a crumple zone ahead of them, which will decelerate the car over e.g. 1m thus a longer amount of time as the front crumples, with a tank there would be little crumpling so the tank stops comparatively much faster over a short distance e.g. 10cm, thus the impact the tank crew would suffer would be an order of magnitude higher as the tank stops BUT their body’s keep moving colliding with the stationery robust interior of a tank vs. the by comparison plush/soft interior of a car with its seatbelts.
Conversely if the car and the tank were to collide with each other THEN the comparative size, weight, strength of a tank given its ~ 40 times the weight of good modern car wins through.
So while armoured vehicles may survive things relatively intact, the crew inside are subject to more forces in some instances even though they are far less likely to suffer intrusions of objects/structures into the occupants compartment, likewise the weight of a tank will help it ONLY with movable smaller objects rather than immovable objects .
You can test this out by jumping up and down on the spot, if you bend your legs as you land you stop slower thus the forces put through your body are much reduced, IF you were to do the same but were to keep your legs locked straight for the landing even from a little jump, you stop much faster and the forces put into your body are much higher as the “stop” is over a shorter distance and time, this is akin to an armoured vehicle hitting something that stops it suddenly with little deformation of the armoured vehicles structure vs. something softer with more deformation colliding with the same object.
As for MRAP’s losing wheels etc, they are designed to do that, as they are a sacraphicial component designed to be sheared in an explosion so the shape of the hull can do its job, also so the suspension mounts on the hull remain intact so they can be put back into service quickly using standard kits when smaller explosions are involved.
Personally, I don’t have any problems with the durability of vehicles or damage to people inside them from colliding with things, given the limited amount of vehicles so far.