From my anecdotal evidence in grad school, this is largely true across many other engineering fields as well. I think some of it is driven by immigration policies and some by culture. A Ph.D. in the US doesn't get you as much respect these days as it used to. Other cultures place more value on higher education.
Also, in a lot of other countries, you can't do much with just an undergraduate degree.
This is pure speculation, but I think the devaluation on PhDs in America might have to do a lot with the large of influx of people in college just attending to "get a degree". I feel this made colleges more of a business than a place of learning with the large increase in revenues, and thus leading to PhDs and fields that aren't as respected or really don't have a basis for being around other than people are willing to pay for it.
Also, in a lot of other countries, you can't do much with just an undergraduate degree.