Why is a worm gear used in a motorized screw jack?

Why is a worm gear used in a motorized screw jack?
Not all screw jacks are driven by worm gears.

Instead of a worm gear it can also be hydraulically operated.

It is used because of the property of self locking.

A Screw Jack Can be operated by electrically or manually.

Electrically-powered screw jacks can save manpower, and control the linear speed.