20+ years ago a neighbor of mine was and inventor by trade and told me his mentor patented the angular road reflector (not the round ones) and got a penny for everyone sold.
That’s my Facebook quality post for the day.
Tee angular reflectors used on California fwys are designed so that at night they reflect white light in one direction and red light in the other.
In other words, if you are ever driving on a freeway there at night and all the reflectors look red - you are going the WRONG way.