Nope. They should relate to each other but do not need to be the same.

Around here the model homes usually show the master bath and the kitchen cabinets the same, the counters relate not the same as laurahahe said. The guest baths are often pedestal sinks and the secondary baths & laundry white cabinets.

I like to see them with different cabinets and counters. Sometimes when they are the same, my immediate thought is that it was a cost saving measure. :/

Bathroom fittings don't need to relate to kitchens or the other bathrooms at all.
I've seen tract houses built that way - but that's typically the lowest-common denominator of home-building and design.

I had this same issue come up with my new home..I have a powder room off a tiny hall not far from the kitchen. I didn't want the cabinets and counter in the powder room to relate in any way to the kitchen..so mine are completely different. I chose to make the cabinet in the same wood tone as the family room furniture which is close by..I went with white delicatus stone for the countertop in the powder with a dark cherry cabinet. My kitchen has white cabinets on the perimeter and a black island..The only way they tie in is the delicatus has a white background with chunks of black and swirls of cherry color crystals in it..