I think quite a few of the leading "western" nations are now "cracking down" of both tax avoidance as well as evasion, following the recent bad publicity regarding the piddling amount of taxes paid by Google, Apple, Starbucks, etc, etc - this was BIG news in the UK (not sure other than the US [where this issue emanated from] what coverage it got). I wouldn't be surprised if the UK Tax Authorities (HMRC) tried to do the same as their Canadian counterparts (they find it much easier to apply the "crackdown" on easy targets - they're targeting that huge tax avoidance scheme at present that is amateur Cricket clubs! [big firms - zip]), although knowing the incompetency of our Civil Service, I doubt if it would have much effect or for long. We'll just have to "wait and see".
It would be interesting to hear from session providers (I doubt if tax/border controls bother to differentiate between session providers who do or do not provide sex as part of their services - its the money they're after) on this issue about any experiences they've had (anywhere) at customs/border controls.