It's also possible at least some of the easter eggs were developed as "off the book" projects, on personal time, and then added to the released software. It's likely the Tesla software developers are working long hours on high pressure deadlines, so if they spend a few minutes on a fun project, wouldn't want to deny them of that...
On the other hand, if easter egg development is using resources that could be applied to fixing obvious bugs (some have been present for years), then that practice should be reconsidered, at least until Tesla fixes the current issues...