That’ll be because the optician has to invest in approx £100k of testing equiptment that the online spec sellers don’t have to
sight test cost = £10-30 depends on where you get it done
sight test cost to optician = £65-70……
is it any wonder they need a mark up on frames/lenses to survive?
If I was in that business, (and what you have said was true) then I would drop the sight tests part of the business??
If its costing them more than double what they can charge for it, it doesn’t make sense to keep doing it.
Just have a shop that sells frames and lenses, cheaper than everyone else on the high street because you aren’t losing a fortune offering a service at a massive loss.