I saw a video of a Russian tank approaching an anti-tank mine sitting in the middle of the road, and they just... drove over it, causing detonation. It wasn't camouflaged at all, it was just sitting there.
I'm not sure what the soldiers in the tank expected. Maybe they missed the "don't drive over obvious mines" day in tank school.
Tanks don't have all that great visibility, soldiers sleep a little in bad conditions, often eat a little + crappy food and are under high stress. Triple so in Russian army by all accounts I read.
Drivers in cars in best conditions fail to notice things, so it is not all that surprising that Russian army soldier would not notice things.
I'm not sure what the soldiers in the tank expected. Maybe they missed the "don't drive over obvious mines" day in tank school.