This constitutes a particular case, and the person who wears socks can just wipe over them. It has also been related from 'Umar ibn al-Khattab and Ibn 'Abbas. Nevertheless, the basis of this permissibility is the practice of the companions and a manifest analogy. There is no real difference between socks and slippers. It is correct that they take the same ruling.
Most scholars say that one can wipe over either one.
Abu Hanifah did not approve of wiping over thick slippers, but he changed his mind three or seven days before his death. Al-Mughirah ibn Shu'bah reported that the Messenger of Allah, upon whom be peace, made ablution and wiped over his socks and slippers. If wiping over the socks and slippers is allowed, then wiping over any foot covering should come first. Whoever claims that there is a consensus on the inadmissibility of wiping over foot coverings does so with a lack of knowledge. Not to speak of a consensus, he cannot prove its forbiddance even from the works of ten famous scholars.