The system hasn't been rigorously policed in the past - it's largely a case of self-reporting. If the team doctor says the rider needs the meds, the UCI doctor will sign off the TUE without asking too many questions. Given the findings of the DCMS committee, UKAD may well decide to open an investigation into Wiggo's TUEs - and Lappartient is talking about getting the CDAF to investigate as well. I don't know how they would prove it, but if there are grounds to suspect wrongdoing, it should be investigated at least.
In some cases in the past, such as Lance's infamous saddle sore as mentioned by
@Dogtrousers, evidence has surfaced of active complicity by the UCI to bend the rules. I don't think Lappartient would countenance anything like that, to be fair, but it's clear that the TUE system still needs further reforms to prevent potential abuse by teams.
I agree with
@Milkfloat that any requests for TUEs should be investigated by an independent doctor, not a team employee, and preferably not a UCI employee either. In fact, I think I already said something similar upthread. Such measures would, however, be costly to implement.