We are talking about who pays, the government are liable to pay, as they the ones who have dictated how and where returning travelers will be detained.
My sister had made arrangements to self isolate for two weeks at her own expense, the government have chosen not to allow her to do so.
The government have no legal grounds to recoup costs from a detainee.
As for my mothers decision to not go, it was more a safety issue due to her age, the risk was too high, (noting she too had stocked up in preparation for two weeks of self isolation).
Unless the government warns travelers before they leave, the government have no right to recoup costs from any detainee.
