These guys aren't exactly the utility company. So in one sense that's good, they aren't the ones taking the call when a tree falls on a power line, or some idiot hits a cable while digging a trench, or your whole street blacks out for no apparent reason. That's a problem for a Network Operator, a natural monopoly which will have emergency contact numbers and in my experience those are fairly good at answering, although obviously only calls about actual problems with their supply network.
The "supplier" for a consumer is actually basically just a bunch of legal contracts, a spreadsheet, a marketing budget and a call centre. And you do end up calling them when things go wrong with that part, which is too often. I usually end up talking to them at least once near the start of a relationship because they got something important wrong, and when I move home or any circumstances change.
It _should_ all be seamless but it often isn't. And ordinary consumers don't understand that it's just spreadsheets, they are genuinely distressed that a screw-up might mean their lights stop working, their food is ruined in the fridge etcetera. So this creates a reluctance to even risk using a different "supplier".
Right now it's super smooth for me, I went to full "smart meter" billing, there's a wireless box somewhere telling what it'll cost when I remember to look and the money vanishes from my current account on cue, no action needed for years at a time (need to review the tarif design, ie mix of fixed and variable charges online every few years or you get a shit default deal). But a decade ago I spent months contesting charges with one of these suppliers because they had a meter reference down wrong in some database and couldn't get the fix to "stick" so I'd get next door's usage billed, I'd complain, they'd "fix" it, same next month, repeat.