I've left my credit card information at I don't know how many web shops, and I noticed that some are very "sensitive": they go to HTTPS as soon as you go to the checkout area, which is good.
Some, however, let you enter your credit card information on a page that's on regular HTTP. As soon as you submit the form, they switch to HTTPS (or so you hope). I've even seen one that redirected to plain HTTP immediately after doing something in HTTPS -- Firefox's nice coloured HTTPS indicator in the address bar flashed before my eyes and was gone instantly. The point is: you don't know in advance whether they will encrypt your data when you submit, or not.
So why don't web shops just do everything in HTTPS? I think it would make me, as a customer, feel a lot safer. Are there any big advantages to use plain HTTP? (Apart from the fact that it's much simpler to set up for the admins, which I don't think is a very good excuse.)
Also, is there any way to find out in advance if one of those "unsensitive" web shops will switch to HTTPS, before I submit my credit card information?