Carrefour - Or: I don't trust my customers

I don't know if you shop in Carrefour from time to time, but I do. When you have bought something elsewhere and you happen to carry a plastic bag with you, the guys at the entrance ask you to put your plastic bag into one of their Carrefour bags and/ or seal it by heating it up - in effect, instead of carrying some else's plastic bag, you carry a plastic bag from Carrefour. Seems to be a good advertisement for them - you eliminating the effort of your competitor and more people carry your Carrefour plastic bag. Does it work? I don't know and actually, I don't care.

What irks me is that I am forced to do it - I am not freely and voluntarily carrying their bag. But what is worse is my impression that Carrefour does not trust you - they seal your plastic bag because they believe that their customer might steal something or put something into the plastic bag and claims that this item has been bought before. While there are people who probably try to steal staff, gosh, they are penalising the rest of the customers!

What kind of marketing is that - what kind of experience? Don't they have an alert at the casheer, alerting them if someone wants to smuggle a product out of the shop?

Wouldn't it be much better, to post some guys at the cashier who asks customers - "Excuse me, have you found everything that you were looking for? Can I assist you in ...". I believe their turnover would grow and customer satisfaction increase.