Vote with your feet and make it abundantly clear that them saving money and wages is not your priority and that you want customer service and the help of a till operator in buying and paying for your shopping.
I was in this morning and almost directed to a self service till by a member of staff and i stood at an empty till, politely refused and said no, you can serve me here thanks.
I'm not being awkward, i just refuse to stand doing what someone else who works there should be doing and i refuse to be stood there waiting for a member of staff to turn up and reset the self service till when it does its inevitable "sorry, computer says no" act.
We had that too, a few years back in Asda. We were waiting at the till, with four or five items on the conveyor belt, third in line - and the security guard (of all people) came over and said to use the self serve checkout. So, i politely refused and said we were fine, and then he says no, please go and use the self serve. It wasn't a request, at that point. i just smiled and said no, i was ok where i was. Pushy little twat had a face like Jamie Carragher after that lol
Was once accused of steeling when using the self serve, because i didn't put all items into a bag and opted to carry a multi pack of crisps rather than bag them - guy followed me out the store and said i'd not paid for all my items - needless to say i had and he got a roasting, i don't appreciate being called a thief or being accosted in the car-park.
i think human contact and sharing a smile (if you can) with a checkout person is important. As a society we're becoming too automated, it's good to share a hello and have a wee chat. I do understand that some people don't want to though, and for them the self serve's may be a preferred option....
As others have said, i've walked out a few times because the self serve is being a dick about some unexpected item or my degree in fruit and veg weighing isn't enough for me to complete the transaction lol, just leave the shopping - life is too short and i have a really big bug bear for machines that don't operate in the same way as i'd expect them too :) so, i just don't use them now.