I might be picturing this in my head differently to the way you meant it but… I am picturing cars on tracks similar to the carrera go slot cars which seem simil

I might be picturing this in my head differently to the way you meant it but… I am picturing cars on tracks similar to the carrera go slot cars which seem similar to trams and trains - which the reason they’re not everywhere is because it’s super insanely expensive to build and maintain the infrastructure of things like that. 1km of train track costs roughly $1B where I live. Imagine the cost of trying to set up the infrastructure of that. Not saying it’s impossible or a dumb idea, but I don’t think many cities would be able to afford to create the infrastructure for that especially not for private use, and imagine the user charges to use that kind of infrastructure and the impacts on the entire system if something was to go wrong.