I smoke weed few times a month. Will have a beer about once, sometimes twice a week. I do pot to get a buzz typically where as a single beer is just nice on a hot day and won’t give me any feeling unless I drink a few in a row. I suspect you never met a person that drinks ‘a’ beer because the same reason you wouldn’t know if a person has a glass of wine at supper. Lots of people do it just for the taste and relaxation and refreshment. Not to get a buzz. There is evidence that is even good for you but I think it is a wash. The occasional one that is. You are likely right though if you know someone that needs ‘a’ single beer a day, they are likely drinking more than that. And I would agree, a full on alcohol addiction is harder on the body then a full on weed addiction.
What I do see is alcoholics will not claim being so is somehow improving their life in an meaningful way. At least they are being truthful. I do know a fair amount of daily pot users, some basically wake and bake, and they are better at suggesting it is necessary to make their life better. I don’t buy that.