While I see the point of your argument
...I'm not totally convinced that is actually what's happening in the real world. I've not been able to dig up any recent statistics; but the 2002 ones that are all over the net and those put UK incidence of MRSA at somewhat under double that of Spain...if your theory were correct the converse would be true and Spain should be blowing the UK statistics out of the water due to 'uncontrolled' antibiotic use.
Therefore, unless Spanish people are unusually wise or UK doctors are extroadinarily incompetent, there's some other factors at work here.
There's 5 that I can think of:
1) The pharmacist can veto selling you anything, and in Spain people often hit the pharmacist rather than a doctors for minor stuff. So if it's a clear case where antibiotics wouldn't do any good, you won't get them.
2) The antibiotics available are strictly limited (Amoxcillin mostly) with the heavyweights being reserved for hospitals and other places that they are needed. The case could be argued that much of the damage is already done for these common classes of antibiotics
3) If you wait until the pharmacists is clear, your disease vector is 1 pharmacist and your immediate family. In the UK the vector is 1x doctor, 1x pharmacist, everyone in the doctor's waiting room and anyone in Boots (unless your GP has a pharmacy built in), plus your immediate family. Whatever you have a dose of -antibiotic-restant or not- minimising exposure in this way HAS to be a good thing and -I would contend- more than offsets any damage done by allowing people to make their own decisions (double-checked by a pharmacist)
4) A course of antibiotics costs €7-20, so it's not like we put it on our cornflakes. There will be a percentage who misuse the responsibility, like normal, but in the UK you'll still have that same percentage and in that case they will be wasting a GP's time while they are about it and will probably still get prescribed something, just to get them out of the surgery with a sense that something has been done.
5) Not everyone is an idiot. According to ECDC
...nearly 40% of Europeans are aware that this is a problem and you can be pretty sure that pharmacists are among that number. So there is an amount of regulation; but you don't have to waste a GP's valuable time to invoke it and it was this -rather than self-diagnosis with gleeful abandon- that was my point.
You can also buy butterfly stitches and burn salve over the counter and so my DIY needs are covered. I haven't needed to see a doctor in six years.