I figure a good percentage of people don’t want to buy sight unseen off the internet. I’ll buy new all day long off the net, but as far as used. I dont trust anybody. Another thing to consider is some of us do not live in heavily populated areas with ready access to a FFL holder. I agree that there are left handed guns available if you want to order, and by several manufacturers, but the fact remains for some they are NOT easy to acquire. And having used right handed guns all my life, I’ll bet that there are not that many that NEED one. If they want one sure, but the NEED is not always there.
Furthermore, you are very fortunate in that you have always been able to find them readily available. In rural America, they don’t grow on trees. I can almost count on one hand the times I seen lots of used left handed guns. My position is that because YOU have had good fortune, doesn’t mean that everyone does.