> That begs the question why aren't we building refineries that can process our own oil

Putting aside the legal and "public appetite" aspects that someone else already mentioned, it all comes back to privitisation in the end.

Given that the extraction was privitised, clearly market theory dictates that you cannot then interfere with where the extracted oil goes.

So if a private company is deciding on refining then it will follow the path of most profit, i.e. build/expand vs use existing capacity elsewhere. Given that most oil companies are large multinationals they will likely also prioritise using their own facilities vs paying a third-party refinery.

And clearly at the time, carbon footprint was not on the agenda of the private companies, either directly or enforced via legislation.