I also note that sprinkler systems are mandated in the US generally above 75 feet. So these systems would not be currently installed in the 4-6 storey apartment building. It would be an additional cost.

Are you using AI to respond to me? Because what you are saying is not accurate

There may be some jurisdictions where this is the case but it's certainly not the case in the vast majority of the country. I'm curious where you got the 75 foot minimum idea? Whatever source told you that, you should probably discount its likely accuracy going forward.