I think we might just have difference for where we place the bar for 'senior.' This does vary by company too. A non-tech company, a tech outsourcing shop in Ind

I think we might just have difference for where we place the bar for 'senior.' This does vary by company too. A non-tech company, a tech outsourcing shop in India, Oracle, Google, and elite startups all have very different bars. At least in companies I've been, someone who can code but cannot design a database, that's a junior backend position, no questions asked. Likewise, someone who can code, but can't do UI/UX design work, that's a junior design position, no questions asked. I think one issue is that if someone has depth in algorithms, computer architectures, and similar, becoming a competent DBA isn't too much work. SQL isn't rocket science, and neither is how databases are organized. If you don't understand B-trees, have background in what sorts of operations to nanoseconds, microseconds, or milliseconds, cache hierarchies, and so on, that's a pretty generally-applicable back-end data set, and you can pick up databases in a few months. That's something I'd expect a senior back-end engineer to have done at some point in their career. If not, I'd hire them in a more junior role, and then advance them quickly. Coincidentally, with that skillset, you can also design something new, like that Facebook back-end. That's also what FAANG interviews try to screen for, although they've had the narrowing effect that people try to master FAANG interview questions, without necessarily that depth. In line with that, I also don't think positions like the Facebook one you described are rare. A lot of positions I've seen require that level of background. I also think you underestimate the number of people at that level.