Signatures are completely pointless. Literally draw squiggles as anyone else can. Nobody ever checks or compares them to the original, how can they?

My signature on a touchpad is noticeably different from my paper signature. It’s been a real challenge for me recently as I’ve had to sign a number of paper documents while the “official” signature on file for me is an electronic one from a touch interface. A few times I have had to resubmit fresh copies when the first ones were rejected.

You could also claim it wasn't your signature and be refunded, but you can't claim that if the delivery person obtained the password only you had.

It's to prevent theft by the delivery person or by the wrong recipient

Signatures are terrible, and especially it's hard to automatically confirm they're correct even if you have a sample on file.

Sometimes I wonder if true reason behind them is not any sort of verification but to maybe increase potential punishment if caught... So effectively nothing...

Increasing potential punishment if caught - or making it more likely that you will get caught - dissuades thefts.