There's more to customer support than picking up a phone.I agree. There is more to customer support than picking up a phone, and some people make it sound like supporting a customer is just reading from the manual.
There's also more to cleaning than mopping. You can employ your philosophy of cleanliness and make things perfectly ordered and spiffy-shiny.
Maybe one day the CEO might walk in and be impressed by your attention to detail, hire you as an intern, and so goes the rest of your success story.
But how much value is the janitor bringing to the company by doing a stellar job? How about customer support? Either hire a stellar engineer and mediocre customer support, or hire a mediocre engineer and stellar customer support. Which would you choose?
When we start talking about jobs, we tend to imagine, in our minds, the people working. Then when people throw out words like "software engineer brings more value to the world than customer support", we translate those words to "you are saying this customer support Jan I am imagining is more valuable than the software engineer Dan I am imagining?"
(Names Jan and Dan were chosen as such because I have seen more female customer support and male software engineers than their counterparts. If you think that is sexism, then you are inherently valuing the human worth of software engineers over that of customer support personnel.)
People's worth is not determined by how much value they bring to the world.
Digression aside, we tend to construct mental models emotionally and attempt to justify with logic.
That is why people include gender in this argument, even though gender has nothing to do with whether people bring value. Again, the software engineer Dan is not a more valuable person than customer support Jan. If you don't get this difference, read No More Mr. Nice Guy or The Way of the Superior Man. The titles are somewhat of a misnomer; I suppose women will gain just as much value from those books.
This is a total shot in the dark, but female engineers are probably paid less than male engineers because they bring less value to the company (read: people hiring) than their male counterparts. The reason why male trait is valued more in STEM is because there are more men in STEM already.
We tend to want to work with people who are similar to us. Thus to a male CEO, he probably prefers a male over female engineer, if they are equal in aptitude. This, of course, is not a right judgment call, but this is humans' default mode of thinking.
There are also job-specific preferred traits. If I were running a hospital, I would pay a male nurse less than a female nurse; female nurses, by their gender trait and societal preference of female nurses (both men and women prefer female nurses), female nurses inherently have more value.
A complex topic that is easily subject to emotional manipulation. But worth talking about.