IANAL…
If they can ask you for proof because you have a big bulky lump in your coat, why can’t they request proof of purchase as you leave? After all, reasonably, a customer may have an item they just purchased, but the store has a shelf full of the same item that are thier property. The difference is that a customer also has a receipt as proof of purchase (and ownership).
The problem is not “is it legal?” Of course it is! You have free speech in the land of the free. The real question is, do you HAVE to show proof of purchase to leave the store with your item? Answer, no. You paid for it, you own it, you can now go anywhere the public is allowed to go. You can even wander back into the store first.
So they ask you to show a receipt and you refuse… dick that you may be, or reasonable but excessively provoked customer, depending on the lineup. The question is, what do they do then?
The answer is - lawyers have made millions on the definition of “reasonable”. If they have reasonable grounds to believe you are committing a crime, they may detain you until the police arrive. Then, your lawyers and theirs and the DA discuss the circumstances and the meaning of the word “reasonable”.
Here are some of the arguments that may be tossed around:
If you are coming from the area of the cash registers, with the item in plain sight, isn’t it reasonable that you paid for it? Especially if the cash register area is laid out so it’s hard to get by with large or obvious merchandise without being questioned?
If it is busy and crowded so the checker would not observe which way you came from, it’s reasonable for him to ask for proof to double check? Busy and crowded is the best time to try and pull of heists, and brazenly walking out the door with something is a time-honoured technique.
If the “customer” is rude, is it reasonable to give him special once-over treatment? Probably not. If he refuses to show a receipt? What other suspicions do you have? Is it merchandise that is often targeted, or valuable? “Unreasonable” behaviour is by definition “not reasonable” in the eyes of the other person.
If you tell the person “leave that merchandise behind or produce a receipt” (aka proof of ownership) and they refuse, does that seem like reasonable behaviour?
If the customer’s rudeness is reaction to unreasonable delays in exiting the store, is it reasonable? Probably.
If they call the police and you don’t even try to prove you have a receipt, is that unreasonable? Depends on the judge. Don’t forget, when you sue over damages, you have to prove you met your “duty to mitigate” - take reasonable (That word again) steps to lessen the damages. If you get arrested and spend a night in jail when all you had to do is reach into your pocket, then the judge likely won’t put all the blame on the store.
You will likely get away without charges of theft regardless. If you have a receipt, case closed. They pretty much have to have you cold taking the merchandise, bypassing the tills, and trying to leave. Even if you pocketed a receipt and ran back in to get a second TV, unless it’s on security video or the serial number is listed, it’s hard to prove you did so beyond a reasonable doubt.
Mind you, we are talking lawsuit against the store over wrongful arrest here. Once the police arrive and ask for proof, if you fail to provide it, then they can only assume there is a reason why you are trying to leave a store with merchandise and no proof of payment. I wonder if it is obstruction of justice to fail to provide police with a receipt in those circumstances. You would definitely be wasting their time.
As for Bozo blocking the door with the cart to enforce checking, that is proof of what sort of person you get when you pay minimum wage and don’t make clear the rules. A lawsuit waiting to happen.
And one final word of caution. When pushing your way past, or pushing carts out of the way, be very very careful NOT to do anything - real or accidental - that would be viewed as assault. That trumps any argument over receipts, theft, or anything… except illegal detainment. And if you use excessive (unreasonable) force to get out of illegal detainment, you can still be charged.