This is in sharp contrast to most commercial operating systems, where you buy one license for each user of the software. The price for a 25-user version of Windows NT is more than five times the price of a 5-user version.
Of course, some Linux software does have limitations of one form or another. Some software is free for personal or educational use, but you have to pay to use it in a business. And some software (for example, most office suites) is commercial and is licensed like most Windows software. (The StarOffice office suite, however, is free for personal use!)