There is a comfortable explanation for why you have never hired a Czech or Slovak engineer, which is that they did not apply. It is true, and it is not evidence of anything about them. The strongest people in that market are filtered out long before you would ever see them, and most of the filtering is done by assumptions on both sides.
They assume the door is closed
Most senior engineers in Central Europe have read a hundred remote job posts that say remote and mean remote in one country. After the fourth rejection that arrives without a single technical question, a reasonable person concludes the category is not open to them and stops spending evenings on it. Your role may genuinely be open to them. They have no way to tell that from the outside.
Their CV was written for a different market
European CVs are conventionally modest. They describe responsibilities rather than achievements, they avoid the metric heavy phrasing an American reader expects, and they leave out context that a local reader would already know. Put that document next to a domestic one and it reads thinner, even when the engineer behind it is stronger. This is a document problem being read as a candidate problem.
Nobody recognises the employers
A US hiring manager gets instant free signal from a familiar logo. A strong engineer from a serious Prague product company, or from an internal platform team at a large European bank, gets none of that. The work can be harder and the scale larger, and it still reads as unknown. Absence of recognition is not absence of quality, but under volume it is treated as the same thing.
The good ones are not looking in public
This is not specific to Europe. Capable, employed senior engineers everywhere move through people they know. In a smaller market that effect is stronger, because the network is denser and reputation travels faster. By the time a genuinely strong person is visible on a job board, something unusual has happened, and it is worth asking what.
What both sides lose
The engineer stays on local compensation while doing work that is worth considerably more elsewhere. The company keeps a seat open for another quarter and pays for that in delivery. Nothing about that outcome is required. It persists because the two sides cannot see each other through the filters between them, and because the mechanism that would let the engineer earn more and the company spend less at the same time is not obvious until somebody explains it.
What changes the outcome
Someone has to do the work of going and finding the people who are not applying, assessing them properly, and translating the evidence into a form a US hiring manager can act on in ten minutes. That is a sourcing and verification problem, not a supply problem. The engineers are there. They have been there the whole time.
We go and find the engineers who never apply, then hand you the evidence. See available engineers.