Governments make the laws though. They can redefine any tax evasion measures to remove their advantage and certainly should.
Of course they can and I and many others including past Prime Ministers, most of the House of Lords members and many Royals would challenge such actions. It is not classed as evasion but quite legal avoidance.
Any politician wanting to put forward a bill to unwind these types of systems would have a hard job in getting any support - most MP's are in deep with avoidance schemes which as I say are completely legal and are not intentionally set up to avoid tax or other financial aspects - that is a side effect and not the original intention.