Lemons are imported so were not cheap and will naturally go off quite quickly. The standard way of having lemon juice for cooking in my childhood 50 years ago was as Jif lemon that would keep for ages in the fridge.
I grew up in a very established middle class family in the 70s and 80s, my Mum was a cookery teacher and even we had a Jif lemon. I think we forget how seasonal food was over 30 years ago and lemons weren't always available, particularly if you lived in the back of beyond as we did. Now of course we always have lemons in the house.
As far as lemons for my gin goes, last January I sliced up all the leftover satsumas and dried them in a low oven (which took forever!) and have them in a jar in the drinks cabinet for my gin. I'm sure you could do the same with a lemon.