but to go through this whole overhead and only have it apply to one airport is totally disproportionate to the risk.
On the other hand, if it's a central vetting process leading to one ID card througout the country (the EU possibly), then this ID card would give every private pilots license holder (who passes the checks) unrestricted and unescorted access to the Heathrow apron as well. (Probably as long as you can claim a more or less credible reason when someone asks.)
I've always wondered about how this works for commercial pilots who need access to their planes via jetways and such in airports across the world. They seem to have one of those magic passes that open all doors.