Premier League

It doesn't stop at the fines. I don't think most of the elite managers would give a tit about a few thousand quid worth of fines each month. But repeated offences would land them touchline bans and it'd only escalate from there.

Besides, as the manager you're expected to set an example for the players. Pochettino said it in his last presser - he fined Jackson for his accumulated yellows leading to a ban and so he had to fine himself for getting one too. If players see the gaffer telling them to not mouth off at the ref and he doesn't practice what he preaches then they're not likely to follow him. More crowding the refs, more yellows, more suspensions. At the end of the day, the club and fans are the ones who suffer.