Self checkout machine seems to be more common in supermarket nowadays and I find myself using them more too whenever I have a quick item to buy. What is interesting is that before at your terminal there would be lots of plastic bags for you to use where on the menu you would indicate how much you took and would be charged appropriately.
It is entirely based on an honour system. Not surprisingly, many people often take bags without paying. So what I noticed recently is that stores have removed all the bags and instead the employees who are normally there to assist people have plastic bags with them. If a customer needs a bag they would get it from them. No more honour system as this way people get billed appropriately.
I think sometimes the honour system simply doesn’t work in a store environment. Even if the mass majority of people are honest it would take a lot of extra sales to make up for a few losses.