no, the machines do take brakes (they aren't being used 24 x 7), don't work from open to close without significant human intervention, and do indeed take days of to get things repaired and replaced. this is the same with all robots.
a 24 hour store needs 168 hours per week in labor (not counting someone to cover breaks)
a 24 hour store in Australia is almost always manned by 1 or 2 staff, who also pack the shelves, order stock, do receiving, sweep the floor, assist customers etc, so a 24 hour store is a bad comparison example. 1 machine would be enough, but again, its wasted funds as a large amount of time the staff are manning the shop is idle time anyway and largely to supervise the customers if there are any.
i'll try and be clearer. 4 machines can do the volume of work that paying a full time employee can (that is, full time hours), however those 4 machines also need a staff member to supervise their function (although 1 staff member can supervise close to 10 machines). and having something wrong with 1 out of 8 machines is pretty typical as there are a lot moving parts and monkeys are hardly a gentle species. so that's a minimum of 9 machines working full time to have a net gain of 1 staff member.
maintenance on 9 machines is more than the $15k a year the staff member is probably worth, and the staff can go and collect trollies when its quiet, instead of just collecting dust.
for a 24 hour store to purchase just one device (which will require supervision anyway) for $30k + $5k maintenance before any work is done for them, compared to paying someone $500 for every week they show up to work. if you sell out, you're not automatically down $30k to someone who is going to tear out your infrastructure and replace it with their own anyway because back office systems aren't compatible with the competitors register systems. Turnover for your typical mom and pop store isn't really enough to justify spending over $30k + $5k ongoing costs for a machine that's slower and less flexible than existing staff, and with a value that depreciates, as a long term solution to staffing.