Being a door greeter is not always easy. I shop at a couple of different stores that have their door greeters check receipts before customers leave the store. I think this is fine, the store is just trying to prevent theft and they have every right to do so.
But I have seen many customers becoming very upset and even yelling and being rude to the door greeters. I think some people feel that they are being treated like a criminal because they are asked to show their receipt. It's also fine if someone doesn't agree with a store policy but I feel so bad when door greeters are treated rudely because of it.
Door greeters are just doing their job and they don't make the policies. I just wish that people understood this and took up their concerns with higher management or the corporates rather than taking it out on the door greeter.