"The decision to hold a referendum is never made by the EU." BUT,
of the 48 referendums held by EU states the subject matter concerned the EU. In the case of Ireland the constitution demands a referendum should changes be required to accommodate EU legislation.

I fail to see why a bar should be imposed. Is it some socialist ploy to
imitate Canute? The existing bar is quite adequate, it is called a majority. It is determined by those that were both eligible and motivated to vote. Strangely enough it is no surprise that "no shows" do not count, neither do ineligible minors. How a majority is determined in the UK referendum is fact-differing opinions have zero substance.