I can see where that fear is coming from. I do have to ask though, how much of this is based on real-life experience?
I wonder because both AWS and Azure (haven’t used GCP so can’t judge that) have been sufficient to say the least. First and foremost, there have been ridiculously few problems in the time I’ve used the cloud, and in particular, the last three or so years have been remarkably void of serious issues. There have been a few bigger service incidents of which I’m not happy, but overall, I’ve found myself to get quite enough nines even for some rather critical applications (real-time LOB apps used at an airport, for example). And most importantly, I’ve got those nines for a fraction of what it would cost to get the same quality of service on-premises.
That said, it is obviously true that if you want a 24/7 15 minute SLA on your cloud support tickets, you’re going to be paying non-trivial amount of dollars for that. Then again, it wouldn’t be cheap on-premises either, and you would also bear the headache of actually running that ops staff — or risk another DC vendor’s incompetence.
