Because they "forgot" to interest them in the results of their work. They are not paid a modest percentage of sales. Sellers who receive their percentage are interested in the results. There are other problems with them. They focus too much on the most promising, in terms of their percentages, sales and customers.
Why can't cashiers / sellers immediately turn on payment terminals (verifones, pin-pads)? Why do they need to be asked about it all the time?
Because they need cash. Because the employer is in no hurry to pay the salary