It makes sense to have a basic knowledge of the language where you will be working... In the case of trucks, not just USA, but even here, if police stops you, you need to be able at least to understand basic requests for papers and problems, if they find something odd you need to be able to explain a bit
Sure. But if the same understanding just happens through an immediate translation anyway, what does it matter?
That would be perfectly fine, I remember some TV footage where an interpreter was taken "on the fly" to do translation between police and a Chinese speaking only his own language... But you need that translation available any time 😄