Off-grid in the city 🇹🇼 (2022-04)

The layman wonders:
Why are diesel generators being used at those downtown locations for long periods of time instead of hooking up with the electrical grid?
Examples
a) Diesel generator at a building construction site operating for years.
b) Diesel generator at a festival site operating for weeks.

Credits:
pexels.com
Tuba Waddle by Audionautix
Creative Commons Attribution 4.0 license
https://creativecommons.org/licenses/by/4.0/
Artist: http://audionautix.com/