Why is blue collar work frowned upon?

Let’s say you work in a high tech office. The building was built by blue collar workers. The windows and doors installed by blue collar workers. The electrical systems installed by blue collar. The preventative maintenance and overall maintenance is done by blue collar contractors.

I may not have been as academically gifted as some people but I don’t think every blue collar worker should be painted inder the same brush. There’s all these stereotypes that we failed school etc. And even if that was the case it’s not exactly nice to snicker at? Traditional education isn’t for everybody.