Totally a keyboard warrior reply, but I suspect that since most of those videos show individual or pair of soldiers, its after their squad was destroyed and these guys are remainder. They probably also hear a lot of drones flying around during the day, so even if they are loud as hell, maybe you "get used" to it and don't react as quick.

Probably don't expect every soldier to carry shotguns so depending who survives the first contact, might not have a right weapon. Also I don't actually know what is Russian squads go to load-outs are. It would be interesting to know if Ukrainian squads who have western training keep up with similar load outs as touted by western armies (where people have roles and equipment to suit). But as we rarely see videos of successful interceptions, its probably not something Ukraine would be quick to share.

Take all this with a ton of salt though, I have no sources, just assumptions. Would be great to hear from professional soldiers with actual combat experience though.