The G614 RST is not a ST tire. Per Goodyear the tire is a LT but its marketed for the "Regional Service Trailer" industry.
The ST tire not designed or recommended for passenger service and is a niche tire so it not surprising feds lumped them in the same category as a tractor/lawn mower/hay baler/combine/etc tire.
By the way the ST tire isn't just for a RV camping trailers but comes on all types of trailers so even if we refused to buy a camping trailer with them as OEM it wouldn't mean much.
Plus many folks have replaced their ST tires with another brand ST tire so ............