In that scenario I think the shop is at fault for calling the police. They have the legal right to do so, obviously, but in the case of a possibly senile man who paid for goods and forgot one item, prosecution is taking it a bit too far,. What do they want, to be a lesson to other senile folks? That ain't gonna work, is it?
I my miss-spent youth, kids caught shoplifting the first time got help by the ear by the manager while he called your mum. Getting caught a second time gave you a free ride in a police car.
Maybe the shop owners need to chill out a little. IMO.
Cheers
Mick