Plastic pipe has made a drastic reduction in cost!
Y’all should have your sales people keeping an eye on rural areas that are expanding public water systems. Dropping the cost of a well booster pump combined with the long fire department response times makes a good sales pitch.
I don’t think they should be nationally mandated of course- there are still significant variables- but they are usually a good choice.
There is currently plastic pipe approved for fire sprinklers (Blazemaster). Also, the prices have finally come down to be cheaper than steel. Standard Schedule 40 PVC pipe though is not approved for use in sprinkler systems.