Pretty smooth process , plus it helps keep someone employed and not me working for my own groceries I’m paying for.

Keeping someone employed for the sake of employment is the exact opposite thing that should happen. If you can pump your own gas, why should you be forced to have someone else do it for you?

I feel like if you have it often your store has particularly bad machines or you're accidentally doing something wrong. Granted there's no tutorial and they have a lot of things that can trip them up, but I'm a daily shopper, sometimes twice daily because it's in close walking distance to me, and I have to have someone come over maybe once a month, and even then it'll usually be for approving something like a gift card or knife rather than an error.

Yeah every time in Tesco it takes longer for me as the badly calibrated scale and cheap crappy scanner fall down. I hate the faux-cheery voice that blares at you while it doesn't work too, you used to be able to mute it but no we all have to listen to that patronising fucker now.

I personally find there needs to be more interaction in self checkouts as they often error meaning you need to wave down / seek out someone to help.

Like what?

There is only 2 instances I've ever need staff assistance. For age check (regular), and when there is a error with the card terminal (very rare). What other errors can there be?