Perhaps this is obvious, but embedded systems.
C/C++ are still really the only languages where you can basically take for granted that you'll have functional tooling and something resembling a standard library regardless of what processor you're targeting.
And many embedded projects still reach for C over C++ because a lot of the functionality the C++ adds isn't really ideal for embedded environments anyway, so for team ergonomics it ends up being better to reach for the simpler language that's easier to teach to new devs, etc.
