You'll perhaps recall that certain British engine manufacturers complained to EASA that the basic elements of the Thielert were not built in a JAR controlled environment and so the engine should not be certified - which tells you a lot about what the rules are actualled used for...
Which engine mfg was that? There aren't many in the UK today.
The "JAR controlled environment" is a load of bull. Anybody with the right authority can buy in a part and certify it by inspecting it and writing out a piece of paper. Otherwise, the aluminium used in a plane with an EASA CofA would have to be made in an EASA approved facility....
It's however true that standards are perversely used to block newcomers into a market. Those who have "reached the standard" (meaning: spent the money on some consultant to generate the paperwork) don't want anybody else to follow them.