You can develop GUI applications using a terminal based toolset, you know. In some cases it doesn't matter what the customer prefers, because the customer won't even know that the software is running.
True, I can develp GUI's using terminal based toolset, I can create GUI's using just C and creating everything by hand, but if you ask the end user if the want to pay for it, the answer in my case is a no. So for me it comes down to a time/money issue.
It is also very true, that the customer usually don't know what OS the program is running, but since, the company I work at, supplies customers with entire POS systems, support and training also matters, so trying to make our customers use linux or something they are not familiar with would mean loosing customers.
True that broswers can do alot, but there area lot of short comings when it comes to POS and creditcard terminals and browsers.
Any way I did not mean to start a flamewar, the question was, what OS and why..