Legality varies by state. For example MD required a spare if one was available, so our 2010 has a donut in the trunk (a $500 option). However no Z ever was OEM'd with RFTs.
RF's are a choice made by the manufacturer in most cases for profit and space. Porsche has their N rating system which they use for OEM tires, and are mostly not RF's (their may be some now a days but not in my 17/18" OEM Cayman sizes
Porsche includes a pump/goo kit, just like BMW has. Theirs just cost more.
Our D MSport was an off lease car we snagged but PO did *not* put RFs on it when changing tires. Thought that was a 'requirement' for leasing a car but obviously every rule is meant to be broken in the name of getting a sale.
I'm personally not a fan of RFT's unless you drive in a high flat risk area, and that seems to be less and less these days.
- b