I would have thought it well nigh impossible to discover if a man has had sex. The hymen can be torn when a tampon is inserted.
Unusual, there's a an opening in the hymen which stretches to accommodate tampons and most young girls start off with 'little' ones anyway. Friends & I used to talk about things like that and a lot still bled from a broken hymen the first time they had sex even though they'd used tampons for a couple of years. The hymen can break for all sorts of reasons, some types of exercise, horse riding, cycling. Not having one intact is not an indicator that someone has had sex.
What you have highlighted is very old fashioned and deeply upsetting for any girl to have to go through. I hope it is stopped but there will always be some in remote places who insist on 'proof of virginity' despite there being no definitive proof. I've also heard of hymens being repaired, the mind boggles.