That quotation pops up on cycling subreddits occasionally and I've always disliked it because I think it discourages people from casual bike riding.

I've been biking to work occasionally for a few years now and it definitely gets easier.

Yeah the quote assumes you're riding without speed limits. In a typical commute, it does get easier once your cardiovascular ability exceeds the upper speed limit given the route.

No, the quote assumes you want to go faster. I don't really. I enjoy my ride and if I wanted to get to work 5 minutes faster, I would leave 5 minutes earlier.

I read that quote as speaking more to the human condition and less about cycling. Humanity has a tendency to keep pushing to the edge of its current abilities no matter how much they expand.

Only if you continue to push yourself while training. What used to be difficult absolutely gets easier in endurance after training.