Yeah definitely they are important, but we also use descriptors for other jobs ("steel worker, medical worker") and I don't hear anybody responding to those terms with "they're workers."
I chose the broadest category but it depends on the context and I realize some might use the narrowest category. I might call the narrowest category something like “full-service sex workers”.
I chose the narrowest category because if someone says "Sue is a sex worker", that's what people will think. But we really need separate terms for the narrowest and widest categories.
"People who have sex in a 'working' manner" - i.e. people who might likely have sex with someone who's essentially a "stranger" to them and be compensated at some point. In a word, my spicy take is that having sex with a SO (or a previous friend) != sex work, with some caveats.