Tbh...yes it is policy and agree stores have a right to protect their profit line.
However, often (student days, working for a green supermarket, allegedly posh) the people disproportionately targeted for these "discretionary checks" were young women, non-white employees.
Some of the male managers were addicted to running "spot-uniform" checks on females, whilst others just walked past them doing exactly the same thing. It's a power thing.
One of the "lads" (managers favourite) "found" £20 that had fallen from a till...nothing done.
A lot of the male managers were as creepy af and saw the female employees (especially the attractive students) as their "hunting ground".
The job itself was a laugh and lots of discounted food and it was nice chatting to all the posh old dears. I actually wish I'd stayed longer as it was good money for what it was.
But the managers were the problem.
A lot of them seemed to have chips on their shoulders about their role not being seen as a "mainstream graduate job"
(the company policy was to put the posh looking people to Head Office after a few months being seen on the shop floor -Andy Street! - so the ones left over seemed quite aggrieved).
They sort of liked being aggressive, and doing petty shitty little things, and putting out vibes that if you were their "favourite", things would be a lot easier.