But then you have to either put it there shortly before an enemy vehicle will pass it, or you have to somehow make sure no friendly vehicles will ever pass it.

They're fighting a defensive war, not a war of maneuver.

Easier to use IEDs and mines when you're bunkering down and the fields are mud -- necessitating the use of a handful of roads.

I'd bet my hat that the reasons the Russians are surrounding the cities and blasting them down is because they know they'd run into tons of IEDs + NLAWs if they rolled into a city.

The big difference is that the Russian army has a strong precedent, and is happy to, blast cities to rubble and kill civilians indiscriminately. It works. For all the collateral damage that the US invasions in the middle east caused, US soldiers generally don't like murdering innocents blindly.