I once "considered" declaring a medical emergency when feeling unwell whilst flying a PA28 into Manchester (UK) one night - long story and irrelevant to this thread.
A subsequent conversation with ATC during a tower visit there a few days later, the controller stated that he would have actioned a full emergency. Big red button stuff.
When his colleagues asked him "Why - for a four seat aircraft", his response was "What if the sick pilot landed on top of a 747 at the hold, or flew through the windows of the terminal building restaurant".