Call me cynical, but if I were to see an art history major switch to programming, I wouldn't think "this is a person that decided he loves CS more than art history", I'd think "this is a person that loves art history and ran out of money."
Of course that's all from the resume. Once you actually meet someone and work with them, you can find out pretty quickly how passionate they are and where their interests are. But we are talking about making judgements off of resumes, which again is why work history trumps all. If someone succeeded at a place with similar requirements to yours, that is a much more important signal of qualification than education, so once you land that first job, whether you were an art history major or cs major isn't so important. Might as well study what you love and then figure out how you fit into the labor market later.
What I implied is that people tend to look for jobs related to their degree if they don't have a good idea what they want. There are those passionate CS degree holders and dispassionate CS degree holders applying for a (say) software dev job. There are probably very few dispassionate humanities degree holders applying to the same job. It's some signal, and I don't think one has to dismiss the importance of a CS degree to see that.
In contrast when you screen resumes you invariably come across people who apparently managed to get a CS degree without learning anything. They won’t be dissuaded from applying to technical positions but if one doesn’t have a CS or related technical degree they probably have some confidence in their own ability.
There’s also a factor where some employers simply pass on resumes if the candidate does not meet strict degree requirements. This also increases the average quality of the non-CS degree holder a bit.