Many of these are based on real world tactics and advertisements.

Photo / ad references:

• Time limited sale - https://optinmonster.com/fomo-marketing-examples-to-boost-sales/
• Fear of missing out - https://optinmonster.com/fomo-marketing-examples-to-boost-sales/
• Fake dress purchase - https://webtransparency.cs.princeton.edu/dark-patterns/

The gross thing is a lot of these are being peddled as best practice.

Time lapse:

Update 2023-05-14: Udemy is subject to a class action lawsuit due to advertising fake sales with time pressure to get you to buy.