>This is not one job, these are three different roles sandwiched into one and you will likely be paid for one role. The major cause for this is often getting Human Resources people to make technical job postings.
Another effect of this, which isn't listed here, is how ridiculously perfect one has to fit the role. A webdev can likely pivot into mobile app development within a month or two. A C# dev can probably pivot into quite a few other languages fairly easily, given their similarities. A lot of subfields in tech have humongous overlaps which really don't take that long to bridge (and vice versa, some don't have a lot of overlap and take a long time to bridge). These practices would instead prefer to lock people in or have them restart their careers from zero.
You see this in the tech interviews as well. Many of them still ask trivia questions which contains a mix of "you only know this if you studied the language deeply" and "you only know this if you used the language a few years, despite the answer being easily found online". Meanwhile, adoption of any framework or language lies at least partially within the ease of picking it up.
And if they aren't specific, their demands are just straight-up asking for an entire IT department.
