Sharing data structures in RAM between 64 bit and 32 bit and 16 bit architectures brings this home painfully. Data communications is equivalently plainful, possibly moreso becaude one has no knowledge of the receiver's architecture. Sending multi-byte values between big- and little-endian machines, for example.

The test could also have included questions on things like packing bools and enums into structures. Again critical to get righht when sharing or transmitting structs, or anything bigger than a char.