Hey-some pharmacies here don't sell condoms. It just goes against their religious principles -seriously-. Regardless of how pissed-off people may get, they have the right to decide what and when to sell it, in the same way customers have the right to decide where and to whom to buy from.
If I had a business with a few workers, it would be easy to establish shifts so my business could stay open all week long.
Salaries - fixed cost
Rent - fixed cost.
As they are all fixed costs, it would cost the same to me to open mon-fri than to open mon-sun.
There are some other costs that are variable: lighting. Heating-air conditioning. etc. Depending on the margin you have, it may very well happen that opening sundays is just not worthwile. Also, it may even be wiser to have satisfied, loyal workers than to have satisfied, random customers.
Internet is not an option in this case. If you want something today, sunday, and your shop is closed, internet won't help you. If you need to place your order on wednesday to have it ready for sunday, you can always go to the shop on wednesday and buy what you need.
The good thing about internet shops is that , most of the time, availability is not an issue and shipping costs are cheaper than the time you spend going to buy the stuff yourself. But with many things like bike shops -or coffee shops-, it is not just about the product, but about the "experience". Going there, chatting with the owner, touching tools, smelling grease. Well Gordon, you get the point.
Personally, I've found myself stuck for breaking a part or a tool and being unable to continue my work. That's when personal traits come to the fore and you either get the mallet or cool down, grab a drink, change clothes and do something else while you write the parts list you will buy -or order- tomorrow just because it is 19:55 and it is impossible to get to the shop on time before those bastards go home... ;-)
My sister-in-law has been a hairdresser for +15 years. I remember her at the beginning staying long hours. Then she had to put the rules and not accept some customers after a given hour, as what they wanted done would take a long time that would exceed the closing time. I remember her telling me that there comes a time when she had to stay firm or some women would arrive five minutes before closing time, after having been shopping or chatting, and want some difficult hairdressing done. My sister-in-law told me that there comes a time that every customer will get upset to you and won't come back, so pleasing them just to losing them in a near future was useless. Also, she told me that it is better to select your own customers, the good ones, and do your best to please them before the rest. The more you can please, the better, but if you can't please everyone, please the best ones.