alt Hacker NewsWindows has garbage defaults, but if you read through their documentation on enterprise architecture they definitely do not recommend having admin be the only account. They do in fact encourage separate accounts, multiple level of privileges with login restrictions across different types of machines, etc.
Many Linux distros are also guilty of this, disabling the root account by default and having the only user have sudo privileges, just like Windows.
Yes, however much more can be done in the user's own directory on Unix systems. Needing sudo raises some eyebrows, whereas most Windows users don't necessarily understand UAC, and almost never think twice about pressing "Yes" on the popups, which are seen more as an annoyance than something critical for safety. Some even completely disable UAC.