Are American gravesites really never reused?

Around here the norm is that gravesites are rented. Usually families will pay to keep the plot for as long as the people who knew the deceased are alive and able to tend to the plot. After that it is allowed to expire and be used for new burials.

It definitely depends. Most of the cemeteries I've grown up around do have some sort of time-limit on plots like that (like 100 years iirc?) - but I mean, I also know of at least two 'memorial gardens' that are literally full and haven't done a burial in years. Presumably these are plots people are still paying for, because the economics doesn't make sense to me otherwise - especially since the ones I'm thinking of are quite literally the nicest cemeteries in my hometown.

Actually looking at their site, one of the ones I'm talking about - which is actually owned and maintained by the town - has sold all the plots and apparently they are either indefinite in terms of time or otherwise not listed anywhere.