that didn't happen with self-checkout tills in supermakets...
This is how the economy often works. The loss of one kind of job to technology lets the business grow by using the same number of staff, or often even more, to serve new opportunities/markets/products/services.
Our population is increasing which means we need jobs to be increasing at same rates. The effect on supermarkets is they get more customers as population increases but they are able to lower the relative number of staff per customer.