[fryguy]

It's not necessarily true. There are a lot of people that take mainly "general education" classes that are required to graduate during the first two years, or alternatively get an associates degree first. Also, given that you're not in a particularly demanding major (like the max-unit engineering degrees) and have a lot of electives, you're not out a lot of work by changing majors within your first two years. Most majors don't have chaining dependencies that take the full four years to complete. For my degree, there was a set of 8 classes that were required to become an upper-division student that only had a 3 semester-deep dependency chain (let's use a computer -> object oriented programming -> abstract data types), and then upper division had around 8-10 classes, and there was only a 3 semester-deep chain (data structures -> processor design -> operating systems). The number of classes you can take per semester is the limiting factor.

Also, considering that people are working jobs and going to school at the same time, four year degrees sometimes take longer. It's pretty common for the challenging engineering degrees to take 5 years due to the sheer number of units required to graduate (I took 6 years, without switching, although I did get a double major in math & computer science).