There are many events in which these bots can't take part like getting free spins or coupon codes with some wagering requirements.
But these bots will partake in anything that they can as long as the requirements are too easy for them to join.
For the normal giveaways also the amount is small and team do it for small promotion to keep up the social media reach so for bots they don't care too much and we can also try as algorithm can pick up any person from the list randomly.
I think that they do but it just so happens that they're hard to avoid and they keep coming no matter what they do. And a way to eliminate their participation is to add some restriction or requirement for those eligible winners.