Nobody eats major appliances either, yet the Star K gives hashgacha to some. Obviously there are halachic issues with appliances on Shabbos and Yom Tov. Phones are a somewhat different issue — there’s nothing inherently assur about a phone. The issue seems to be how it’s used (texting to find out zmanim is OK, texting to flirt is bad; Internet to listen to shiurim is good, Internet pornography is bad). The whole kosher phone phenomenon is based on the premise that given the opportunity, people will behave badly (which may very well be a valid premise).