And don't forget the real crux of the problem: Do I even know whether a specialist is good or not? Hiring experts is really difficult if you don't have the skill in the topic, and if you do, you either not need an expert, or you will be biased towards those that agree with you.
It's not even limited to sysadmins, or in tech. How do you know whether a mechanic is very good, or iffy? Is a financial advisor giving you good advice, or basically robbing you? It's not as if many companies are going to hire 4 business units worth of on prem admins, and then decide which one does better after running for 3 years, or something empirical like that. You might be the poor sob that hires the very expensive, yet incompetent and out of date specialist, whose only remaining good skill is selling confidence to employers.
> Do I even know whether a specialist is good or not?
Of course but unless I misunderstood what you meant to say, you don't escape that by buying from AWS. It's just that instead of "sysadmin specialists" you need "AWS specialists".
If you want to outsource the job then you need to go up at least 1 more layer of abstraction (and likely an order of magnitude in price) and buy fully managed services.
This only gets worse as you go higher in management. How does a technical founder know what good sales or marketing looks like? They are often swayed by people who can talk a good talk and deliver nothing.
The good news with marketing and sales is that you want the people who talk a good talk, so you're halfway there, you just gotta direct them towards the market and away from bilking you.