In Singapore if you previously worked at Google you were golden even if you were a goddamn moron and technical tests were done incredibly badly or not at all. I could see why people didn't improve their technical skills and why expert beginners were omnipresent. Nobody was going to reward them for it.
In London that sort of thing exists too but companies that interview on merit rather than pedigree did at least exist and weren't extremely uncommon.
I have limited experience of SF but I expect it is more like London than Singapore.
Leetcode was common in Singapore, because if you google programmer questions that's what comes up.
DC's a tech hub, people from SF and NY just don't realize 'cause they don't know 'bout that government contracting ecosystem.
This is a side effect of having non technical managers. They cannot judge your technical skills beyond a certain point. They can judge your people skills and domain knowledge. They reward improvements in what they can judge.
The above doesn't apply in tech companies and in tech hubs. It applied to me when I searched for jobs in a relative backwater only (and as somebody who wanted to advance technically it was frustrating).
This is why I think you'd be more likely to find expert beginners in Maryland or Singapore than in San Fran or New York.