Why Are Large Decorated Graves So Common in South Asia Despite Islamic Teachings?

As-salamu alaykum. I’ve seen a lot, both online and when visiting family, that in many South Asian Muslim communities, people build huge graves with domes, lights, and fancy decorations. Some of them almost look like shrines or even temples, may Allah protect us. What bothers me is that folks go there, seem amazed by them, and sometimes even make du‘a right at the graves. I get that some say Salafis are extreme and that in the past they flattened graves, but I can understand the worry because things like this could lead to shirk. From what I know, the Prophet Muhammad ﷺ clearly told us not to go overboard with graves or turn them into places of worship. So I’m puzzled why this is still normal in some areas. Is it because of local customs, not knowing the deen well, or something else? I’ve come across this in other countries too, but it feels especially widespread there.