Likewise, but the issue there is slightly different — if they had ruled that “burgers” had to contain meat, there would be a similar but stronger argument to force “hamburgers” to only refer to those made of ham.

Hamburgers are named after the place they were invented (the city of Hamburg), itself named after a big castle which in German is “Burg”.

And before anyone suggests one could also argue that “they’re only allowed to be called hamburgers if they’re from Hamburg and otherwise are just sparkling fried meat patties”, I apologise for spoiling the obvious joke by having looked up the EU rules for when something can be protected with a geographical designation (feta cheese, champagne, etc.) and discovered none of that sort of thing would apply.