Jobs were a lot more local, too. People didn't move around as much. In general, not just in software. You also couldn't just spend a couple minutes and get a ballpark for what employers were paying in another city, let alone get a decent sense of what a bunch of markets looked like—it'd take some real effort. Reduced mobility and information being much harder to come by kept salaries lower, I expect.
Was it? In 1995 I was shocked to discover what the “computer guys” were getting paid, and decided I ought to be writing code (etc) as my official job instead of just the thing I do within my other job.
