The word “garage” can be very misleading in these threads because an outside storage compartment large enough for bikes under living space (garage to British) is very different than a toy hauler garage to us in US.
There are a lot of American motorhomes with large rear storage compartments under the beds, but what makes them a “bike garage” to me is when the compartment is tall enough to haul bikes upright (without having to lay on sides). That seems to be what Europeans also call a garage, which are at least 1-meter tall (a minimum of about 39 inches of clear height).
A flat “bike garage” floor is also very common in Europe, but in US manufacturers often leave the chassis frame rails (or frame extensions) running right through compartment, easily losing up to 10 inches of storage height.
My engineering guess is that US manufacturers feel that in addition to saving cost, they need straight chassis rails to increase ground clearance at back of large motorhomes with long rear overhangs so they don’t drag on pavement, and also to increase towing capacity. In smaller European motorhomes, neither of these issues is nearly as much of a problem.
If Thor or any other RV manufacturer is going to design a compact motorhome with a proper “bike-size” garage, they need to make it a design priority from the onset, not just an afterthought.