What would make you trust a cloud solution over on-prem?

From a small business perspective: you may not have anyone competent to manage hardware. I know of two companies that had a great hardware, but the single employee who managed it moved on. Some time later, things failed, and there were no useful backups.

Alternatively, even if you have a good techie, you may want more reliability than a single server in a closet.

I have helped various small businesses. Sometimes cloud is the right choice. Sometimes not. Depends on the situation.

Having worked with both on-premises and colocated infrastructure, then having to deal with the problems that come from not having cloud scale redundancy because it costs too much and requires a lot of ongoing maintenance.

It’s not really a question of trust, and you will have to define what you mean by trust. It’s a question of economies of scale, and the difficulty hiring and retaining people competent to manage infrastructure.

Depends on what, exactly, you mean by "trust", I think.

Personally, I can't think of anything that would make a cloud solution attractive. They provide too much downside for no upside to me.

However, I could imagine use cases (that I don't have) that would make using a cloud solution a reasonable thing.