When on federal or state land, I only have to comply with the state's laws. (Basically just don't shoot or threaten anyone.) When on reservation land, I'm protected under the FOPA[0] which is considerably more restrictive. Some of its provisions can be hard to meet. Especially in a two seater pickup truck.

Add checkerboarding[1] to this and it can be very easy to make a mistake because you're constantly changing jurisdictions. Usually with no fence or signage.

I don't want to get into it here but there are a number of reasons one might want a readily accessible firearm when the nearest civilization is ~100 miles away.[2] Hence why one might not always be compliant with FOPA.

[0] https://en.wikipedia.org/wiki/Firearm_Owners_Protection_Act#...

[1] https://en.wikipedia.org/wiki/Checkerboarding_(land)

[2] A benign example would be hitting a cow.