Sure but a non-vegan can absolutely comprehend putting their own convenience over the well-being of an animal. Downvoting won’t change that.
Ditto with vegans. Being a vegan doesn’t magically make someone not an ass.
IMO, not being able to comprehend cruelty makes someone an ass. The dude in this story could have been kind, polite… they could have helped mow the lawn of their elderly neighbor that’s no longer able to do so themselves.
Regardless of how otherwise good you are treating a pet that you’ve accepted responsibility for and who, potentially, fully trusts you as family like this… that makes you an ass.
Anyways I think my only real objection to your original statement is that I don’t think veganism is relevant to this story. I’d say that vegans are more likely to treat their pet well but it’s not a guarantee - even among vegans that made that choice for an ethical reason there are still assholes.
Pick a lane. Convenience does not equal cruelty.
On being able to comprehend, there are human conditions that are beyond my comprehension. I mean as an intellectual thought process I am aware why some people do certain things but it is so far outside of my experience that I could never truly comprehend why.