The best way to know who owns the service you use it to own it yourself. That does come with a lot of overhead, though. I started my own kbin instance because I, like you, was worried about "what if one day I go to login and my home instance decided to shut off forever?" That can't happen now, besides if I forget to pay/something goes wrong with the server. But I enjoy tinkering so it works out in my case.

I think ultimately users are responsible for which instance they choose to sign up for. If there isn't much transparency on a certain instance, it may not be the one for you. I agree that the sign up pages could have some areas where more information could be shared. Of course, it is up to each instance admin to share accurate and factual information as to who they are/where the money comes from/goes etc.