Anyone who benefits from it still pays UK tax on all UK derived income. They also pay tax in the countries where they also earn income.
In the absence of the non dom rule, they would still get credit against the UK tax bill for taxes that they have paid overseas (double taxation), so we still wouldnāt receive tax on their entire worldwide earnings
It is also a devilishly complicated aspect of tax law so I wonder if the non dom status was a quick and easy way of getting some revenue without tying up legions of HMRC inspectors arguing the toss with these peopleās bean counters
As for Rishiās dishy - she is an Indian citizen (not a a British one) so she probably has a more legitimate claim of non dom status than say Lord Ashcroft