Calling it polyurethane or polyvinyl chloride sounds less weird to some, more weird to others.
synthetic leather
No clue why 'vegan' products value adjectives to meat so much.
probably because synthetic sounds/is chemical and the producer wants to also market this to the "only natural products are good" crowd which probably has an overlap with people who are vegan.
That's pretty ironic since most vegan products have significant basis in chemically enhanced flavour and nutrition