There are several options on that Czech site. You can just have the CD + fancy package mailed to you plus, if you choose the more expensive option, you will also get the license voucher code (e-)mailed to you too.
It's not illegal, it's just that why should I pay for a CD and then wait for it a couple of days, when I can just click the download button and have it for free in a few seconds.
On the other hand, this is quite useful for people who cannot or don't want to pay over the internet and prefer COD or bank transfer to an account in Czech Republic (which they might find less suspicious).