Software engineering isn’t blue collar work. “A blue-collar worker is a working class person who performs manual labor. Blue-collar work may involve skilled or unskilled labor.” https://en.wikipedia.org/wiki/Blue-collar_worker

Plumber or nurse sure, but staring at a screen or moving Post-it notes isn’t physical labor.

While wrenching on a car is indeed manual labor I feel like it can take similar levels of mental effort, background knowledge, and training as junior dev work. So the parallel isn’t entirely off base. I believe the OP’s argument is that there are new classes of work that didn’t exist back then. Perhaps they’re not as cleanly sorted into white and blue collar lines as before but they occupy similar places in the socio-economic status positioning.

Being a mechanic is extremely repetitive. Occasionally people are faced with something odd, but it’s mostly a checklist job because identical makes and models generally run into the same issues.

Or as a childhood friend out it. It’s boring, but I can zone out and work with my hands.