Yes because it would make the company more money
Not necessarily as it would require a liquor license and new training for employees, and since people don't tend to go to McDonald's seeking alcoholic beverages wouldn't necessarily generate enough sales to increase revenue to cover those increased expenses.
You only need to pay for those things once. And the training is not extensive, it's literally just telling them they have to card anyone trying to buy it who looks under 50 or whatever.
Liquor licenses have to be renewed annually and are often capped per city or county.
I think that depends on the state. Like in New York it's obviously not a barrier to tons of random stores selling beer plus pretty much every chain like Target and Dollar General.
I think there's a distinction between
selling alcohol and
serving alcohol. At least depending on the state. Minnesota's are pretty strict, only authorized liquor stores can sell alcohol and the only Targets or grocery stores that do are ones with an attached liquor store with a separate door. But serving alcohol to drink requires a liquor license in all states, and I've never heard of one that doesn't require renewal. Pennsylvania btw caps liquor licenses in the state so if it's maxed out (as it is now and has been basically forever) the only way to get a license is to buy one from someone else, so closing businesses will auction their license and it often goes for like $25k....it's probably not even feasible for every McDonald's in Pennsylvania to serve alcohol.
Also it's not just telling employees "card people". They also have to be able to spot fake IDs and the like. A bartender friend of mine told me about some things on Minnesota driver's licenses that all legit licenses have such as that the last two digits are always the number the first three digits on the ID add up to (for example mine is 288 at the beginning and ends in 18.) That's not difficult to train either...but do you really want some minimum wage untipped worker who's the sort of person who has to work at McDonald's being all that's standing between you and your business getting potentially a $20k+ fine? Because that's something every franchise owner would have to deal with. Also in most states this would effectively ban anyone under 21 from working at McDonald's, at least at the front counter. (I know in many states under 21 cashiers can ring up customers buying alcohol, but I don't know of any that allows under 21s to actually pour and serve alcoholic drinks. Some might allow under 21 waiters and waitresses to bring drinks to a table but not actually prepare it.)