Puzzeled
Well that's an interesting question especially in light of the announcement from Canada.
H&M in their "declaration of independence" made much of retaining security indefinitely because they were "Internationally protected persons".
Canada has come right out with it and said no. If you are not royal you are no longer IPP's.
As to why you wouldn't just have Canadian (or US for that matter only security) for IPP's is not because they are inferior or incapable. Far from it.
Rather the issue for an IPP is that there should never be a conflict of interest wrt their protection, something only their "home country" can provide as the principle security provider.
This is why Canadian CPO's can support the Met whilst they are in Vancouver but they won't take point.
If there is now a general understanding they are not IPP's then the Met (much like the Canadians) has no obligation to provide free security.
But that still doesn't change who Harry is and the fact he needs security but if he's not an IPP then theoretically there should be no issue with Canadian security (which the U.K. taxpayer could fund at current levels with H&M or the RF topping up).