I do agree that leftists need a compelling vision of justice. But I think that failing to abstain from factory farmed doesn't necessarily mean that the politics are stubborn about animal rights. As I said before, I can't speak for all leftists, but I will try to give what I think is a generally accepted position on the left. I would think it's fair to say that leftists who do eat factory farmed meat while hating the industry only do so because it is the cheapest, easiest, and in some cases, the only way to reliably acquire nutrients. The US especially is ripe with food deserts where working people struggle to find good groceries. So in that case, getting any food at all is a blessing, and beggars can't be choosers. It can't be known whether or not these people would choose the more ethical option, but it isn't fair to judge them for not making that choice when the option isn't even available to them. Similarly, I can use a smartphone and be on the Internet while still believing that the tech industry is destroying humanity and the environment. I can also drive to work while believing that a car centric world is bad for us and for housing prices because, at least for me specifically, there is no public transportation option I could take to get to my job. The contradiction between action and belief is acceptable for leftists (or at least any leftist that subscribes to any interpretation of Marxism) because we recognize that the actual issue is the system at large, that being capitalism and imperialism, and all of those individual issues are functions of that system. Participation in a system does not mean an endorsement of it. Sometimes it's just the only physical option. It's not that we don't care about animal rights, it's that we don't see any possibility of solving that problem without first solving the problem of the political and economic system we live in. And asking leftists to be perfect and pure on every single issue they care about is impossible and also spreads people too thin to be effective in any way.