They do ..

Shimano tandem hubs are in 40 and 48 spoke , they come as a 145,
but can be narrowed down with a few parts swaps, like a 135 axle , skewer,
and a few shorter spacers on the left end
Myself,
I put a decade of loaded touring trips on my Phil Wood 48 spoke freewheel hub, seven speed freewheel.
specialized 40 spoke front ..

I bring my wheel builder under my hat.