How come Tyre Pressure Monitor Systems are federal law in US for all new cars and trucks beginning 01. September 2007, but not required on commercial aeroplanes?
Maybe it is because an Air Operator Certificate Holder has commercial aeroplanes maintained under an Approved System of Maintenance.
My (fairly new) Boeing does not have TPMS. But it is subject to a daily inspection by a licensed aircraft maintenance engineer prior to each day's flying, and it gets a once over at every turnaround from a licenced aircraft maintenance engineer...
I'd say the road transport people are catching up with us aviation people, rather than leaving us behind in the maintenance and safety stakes.