Why is ecommerce software so crappy?

so I’m pretty much banging my head against the wall. I’m trying to get my first ecommerce site of the ground for a designer friend. I’ve looked over and installed a half dozen crap-tastically coded products… oscommerce, zencart, veracart. hate em. table based code and I’m going to spend half my life removing all the crud I don’t need.

I just want a very simple cart that I can customized the appearance of easily. any suggestions?

thx - b