Because I have just had a revelation after seeing a photo on the Uniqlo website of someone stepping into a top like a one-piece swimsuit. They are very comfortable for summer but I have limited mobility in one shoulder and I found them a struggle to get on and off. So this morning I dug out one of my vest tops and tried it the other way, and it's so easy, I can't believe I never thought of it before. The shoulder straps are very light-weight lace so they take a bit of untwisting once it's on, but that's minor compared to putting it on the other way.