Interesting post. I can see it getting very repetitive but I'm surprised there is sales pressure. I've been going to the opticians since I was four and the optometrist has never, ever pushed me to buy anything. There are salespeople with zero clinical experience or training to try and sting as much money out of you as possible.
Your point about working weekends is pretty silly to be honest. Healthcare is 24 hours so optometry is probably one of the best professions for working hours. Virtually all other frontline staff have to man a 24 hour service.
I'm guessing your professional union is weak if the big boys have pushed down salaries and working conditions so much?