What I don't get is how they're so unreliable. My buddy has been making his own EVSE and there's really not much to it. Anyone know what's their primary mode of failure? Is it just crappy software written by lowest bidder or?
For regular AC-charging all the logic is in the car, so the only thing you really need is some safety features on the outside, typically some ground fault protection and so on. But when you use a DC fast charger the charger itself and the cars battery management system has to work together, which I imagine can cause all kinds of edge cases where people have interpreted the standards differently. It didn't help that there were multiple different standards early on.
To be fair though, the Mer stations did say "out of order", was just the Circle-K ones which didn't show correct status.
However, when driving alone you don't have the luxury of checking the app while driving. So in almost all cases you don't find out until you're there.
Out of interest I occasionally try to charge at a non-Tesla charger and the experience is dismal with a roughly 50% failure rate. Sometimes the charger won't start, sometimes the payment system won't accept my credit card, sometimes the app doesn't work, sometimes the touchscreen is simply not functioning.
But things are definitely improving in the UK at least. But another problem is that the cost of charging at many motorway service station fast chargers makes refuelling about as expensive as driving an ICE car. Tesla is noticeably cheaper than the other networks.
Yet not all of them, so it wasn't a common cause as such.
edit: This was one of the worse cases, but it's not infrequent I experience at least one charger at a station out of service. I would say it's rather seldom I charge on a station where all chargers work.