Imagine that you are Nicola Sturgeon. You have every reason to believe that an independence referendum would pass if it were held today, but the British government has no intention of permitting one. The arguments in favor of British independence from the EU do not, it seems, apply to the Scots. What do you do?
Your decision is informed by two precedents: Catalonia and Ireland. The first tells you that unauthorized referenda don’t end well, and that you can’t expect any support from the EU. The second tells you that success is possible if your political efforts are backed by widespread violence. You don’t have any interest in forming an SRA, so the terrorist option isn’t on the table.
You have two choices. In the short run, you could try to coerce the government with a general strike. The problem, of course, is that you don’t have the kind of unanimous public support that you would need to make a general strike work. In the longer run, you can hope that, at some point, the SNP holds the balance of power in Westminster, and that Labour is desperate enough for power that it will agree to a referendum.
Is the latter scenario likely in the foreseeable future? No. But what better option do you have?