It's because - as you admitted earlier - Bama typically walks on the field with superior athletes coached by superior coaches, yet somehow the other teams never have to hold the DL and LBs that almost without exception end up playing on Sundays.
It's not a black or white issue - we admit that everyone gets away with penalties - but when a team that's loaded with players that should, if anything, require opposing players to grab a jersey or whatever in order to block them or get past them is dead last in opposing penalties against, it makes no sense. If anything, Alabama should be on the upper end of spectrum wrt opposing teams getting penalized trying to get by or stick with the bigger, faster players Bama generally has.
Yet Bama has been ranked dead last not just in the SEC, but in all of FBS for the last two years in opposing penalties. It's inexplicable outside of bias - there's no way each and every team elevates their level of execution to such a high level only against one team...