> The UK had so many carve-outs and exemptions

The EU had many things that didn't benefit the UK, which happens when you don't share a mainland with the rest of Europe. e.g. Schengen area didn't make as much sense for UK,

The UK got to not adopt the euro, but then it's currency was particularly strong in the first place. The Rebate is usually what is spin as the great advantage given to the UK, but was mostly justified by the fact that the UK didn't benefit as much from agricultural subsidies.