Similarly, batteries for all the various electronic gadgets are standardised. You can go to a corner shop in Tanganyika or Tokyo, as well as Toulouse and it will fit. That has not happened by chance.
This concerns a lower tech product – jam
Doctrinaire free traders appear to believe that tariffs are the main problem.
It is quite obvious that there are far too many regulatory details to negotiate on an item by item basis and such matters will have to be dealt with as a package or off the peg deal.
In whole or in part, the only body of law which contains all these all together is the EEA agreement. It would be relatively simple to do the job ” off the peg with alterations” by making deletions or additions to it but to open the whole can of worms would take many years.