Because Rover is all about looks over function.
Also Range Rover is British, built by British engineers, towing is not a common requirement there like it is in the U.S.
Its an after thought to adapt to the U.S. market.
When I was stationed in the UK I probably saw less than 20 trailers being towed by non-comercial vehicles in a 14 month period.
Definitely not like the U.S.