Velomobiles exist. The rotovelo is probably the closest to being designed for massproductio , but it's still about 3x that target.

But 30mph is too much for dedicated bike infrastructure and is just turning them into roads (although I support LEVs and LEV only zones, they're still not bicycles). 15-20mph is a human scaled speed limit where interactions are far less likely to cause accidents and impact energy is low enough to rarely cause major injury. It also makes enough battery for range trivial and makes the vehicles that become status quo far lighter and less dangerous.

A golf cart has to travel on the same roads as a car, except it's slower and less safe. No advantage really.

Anything travelling 30mph has to travel on the roads. Class 3 ebike owners who ride on shared use trails are a menace and a serious threat - to pedestrians, to other cyclists, and to any goodwill cycling has in the community.

Heck, I get sometimes overtaken by people riding illegal (in EU) ebikes on a bike path. Mine is heavy duty enough that it can maybe do 30 kph with leg power. Theirs do 45 kph and it's getting dangerous.

Mostly delivery people use those. The lanes are narrow, so if there's oncoming they would likely crash...

I am currently living in a seaside town where golf carts are a normal means of transportation. You see them out and about every day. On the main highway through town, they drive on the shoulder; everywhere else, they take a lane just like cars do. The people here clearly believe they have some advantage.

Slower is safer for pedestrians. It's safer alternative for (?) elders than a full featured car.

Changing lanes will be pretty difficult if the golf cart is much slower than general traffic.

Yeah it's pain as a car driver. There's no ideal solution.