I think the problem with Tunnels is that they look like a quicker, safer, more intelligent way to get to A to B, and the rovers won't prefer them. They FEEL like a far superior option to get supplies and machines to where they need to go, like they should be filling the (unfilled) niche of some kind of highway system, rather than purely accessing inaccessible areas.
This isn't a problem with their programming per se, but it is a problem with the optics as a player. There's a lot of games that use a mechanic like that in exactly that way. And there's a gap in the logistics system in Surviving Mars that Tunnels used in that way (as a short cut) would actually fill. So the fact that it feels like the programmers deliberately avoided making that function a thing is kind of baffling to players.
As a general thing I feel that transport between the domes is incredibly unfinished and undeveloped. People look at the system you created and want a transport system between domes, and Tunnels looks like it might be that system, except it's very deliberately not.
Mass transit would absolutely be a thing between domes in an IRL version of this game, whether it's rail, subway, or something more exotic like zip lines, so the fact that your choices are to rely on the inconsistent shuttle network, or have your settlers die of asphyxiation because it was such a lovely day they decided to walk, gets frustrating rather quickly because there's no system in place designed to allow you to do anything reliable about it, and there danged well should be.