Sure.
I'm finding this really hard to articulate, but here goes...
I feel like this should be self-evident, but we've been trained to think otherwise, to believe that giving so much of our time and energy is completely normal or even noble.
I've worked with my hands and with my mind, as a full-time employee, a union member and an at-will contractor.
There's actually nothing terribly special or unique about thinking for a living - it's still work with energy and opportunity cost for doing it. When the toll is primarily mental it's harder to perceive, but just as real.
The big difference between knowledge workers and everyone else is what individuals and workers as a group will put up with.
Tech workers accept being sent home with laptops and cellphones by an employer who doesn't want to pay three shifts worth of coverage for a 24/7 operation. Elsewhere this is prevented by unions, regulations and the implicit understanding that allowing the next man to devalue himself today will devalue the group tomorrow.