I'm not missing the implication, because rooms don't have to be clean simultaneously. Bacteria aren't actually all that mobile - most transmission is from touch contact with surfaces (or patients, who are themselves surfaces). Major disinfection takes place when a room is vacated, and it gets done - there's no reason to suggest that a cleaning staff doesn't scale with hospital size.
What's far more important is the quality of the room disinfection, which again, is a property of the room, not the number of them.
As for dedicated teams, I don't see why such things couldn't exist on a city-wide basis if they were useful.
Because now all you've done is taken the same workload, and said "Now you need to deal with 5 different smaller hospitals, five administration schemes (two of which don't like you), travel time, etc. Smaller hospitals do do this, sharing their burden between them, but a dedicated team has been shown to perform better.
And for specialized high risk disinfection teams, you've now suggested both that rooms need to be cleaned simultaneously, and that having a team across town is A-OK. Pick one, you really can't have both.
The lousy and getting-lousier quality of American healthcare just generally indicates that hospitals don't put profits from economies of scale or whatever else back to real improvements in safety - though they apparent put a lot of money into meals to entice returning patients (fancy meals - visible, real safety - invisible).
This really isn't true at all. Because hospitals aren't reimbursed for hospital-acquired infections, it costs them real money, and there is intense interest in improving patient safety. MRSA rates have been dropping, antibiotic stewardship programs are better, hand-washing rates are much improved, etc.
Fancy meals might be visible, but a bad case of C. difficile will cost a hospital many, many thousands of dollars. They're interested in preventing those types of infections.
I know because I work with them doing exactly that.