(also 100% British is a very good point! I've had people ask me to make a four house system for a Japanese school of magic which is...?? not a thing they would do?)
Hm, good point that the whole "let's sort people" urge is also at least partly cultural, in addition to this particular sorting system being tied to one specific culture! (In Finland, division into houses would be alphabetically by surname. At most, in old times, based on region one hailed from.)