Some thoughts make someone wirelessly attest to their identity via their phone if they want to be allowed to come into your location. If someone while inside your establishment walks out with the merchandise then suddenly every store in town auto locks their door when they approach or wont unlock if they approach without their phone.

Make it appealable in case of issue but if they have you on video you pretty much aren't winning.

If more people than phones approach the door just don't open and play a verbal warning preventing tailgating.