You can get canvas shoes for less than a fiver here in the UK easily enough so it's hardly true to say that non-leather footwear is prohibitively expensive. Also, synthetic safety footwear isn't hard to find if you care to look.
Sportsdirect is a place you'll find on the high street of any big town or city in the UK; loads of cheap shoes to be had.
I think that discussions like this (namely, claiming that if someone is not absolutely perfect they can't call themselves vegan) keep more people from trying out veganism. And this makes me sad. I don't wear leather, used or otherwise, but I don't have any leather from my pregnant days because it was never my style. I don't feel that this makes me any more vegan, or a better vegan than someone who does otherwise. Calling out people who are trying to do a good thing is not helping animals. Veganism seems like a major lifestyle change to many omnis, and if they get overwhelmed by details like old leather products it can discourage them from even trying.
It's got nothing to do with striving for perfection. One of my kids has to take medicine every day ( & potentially every day for the rest of her life) for a serious health issue & obviously this product will have been tested on animals; this is a world apart from someone choosing to continue to wear leather when it's completely unnecessary & avoidable.