I hope he was just confused and meant that a 110v 15a typical wall outlet in the garage type outlet is "not enough". Even a 20a circuit will only run the 13.5k a/c and that's about it. And, that depends on the guage, and length of the extension cord (if any).
Oh, and lets not forget that if the "home" shore power is GFCI protected, and you plug the trailer (which is also GFCI protected) in to it, one of them (usually the shore circuit) will trip at the slightest variation in current. May not happen right away, or may not happen at all but, is highly possible eventually. I had this happen to me twice at two different locations (a friends GFCI protected garage circuit and my own home's GFCI garage circuit). He's an electrician and told me GFCI,s "don't like each other" when hooked to each other.