Why do you need the entire integrated setup to be outdoor-rated? That just adds tons of cost. If the antennas and modem need to be outside for signal strength reasons, so be it, but as much of your networking gear as possible should be indoors.
There are brands specifically for those markets though. Complaining about Ubiquiti not making a product for that specific use case feels like complaining about a Honda Civic not being an offroad-capable Jeep.
“The UniFi 5G Max lineup was created with a clear goal in mind: deliver a sleek, versatile, and exceptionally powerful 5G internet experience that works effortlessly in any environment.”
If it’s fine if you want to build a golf cart, just don’t pretend it’s an ATV.