I'm sure that people can get paid to code simple, well defined stuff in a very high-level language/script without formal training but "professional software dev" implies a level of knowledge and competency that is far beyond knowing how many bits are in a byte, which frankly is "teenager interested in computers" level of basic knowledge.

In fact, IMHO a professional software dev will be reasonably proficient in binary and powers of two in general as a matter of basic knowledge.