about 20 years ago or so, I recall American coming to KSFO...flights were declaring ''min fuel''...perfectly legal to do. Bay approach (now called nor cal) said: fine, you are blank flying miles to the outer marker, if unable say alternate.
No short cut was given. It was a simple transfer of information.
But, a declaration of emergency puts a pilot back in the driver's seat. IF he has to, he may violate , to the extent necessary, the other regs. At that point the pilot could just go to the airport and land.
But then the questions start.
There were soooo many American flights on min fuel that instead of flying distance given, ATC would just say: roger, expect vectors to Oakland (the airport across the bay from San Francisco)..
American wanted to save money...went with min fuel. All legal.
In the final analysis, the FAA is responsible. Do you want no problems? FAA should increase fuel requirements for certain airports...and that's all she wrote.