Why applications in PlayMarket weigh little, unlike mine?

Question

Android

Why does the normal Hello, World base app weigh 12MB when I go into settings and check the memory. And applications in the play market weigh 1,2,3 MB each, although there is content there!

Answer 1

1) You may not be doing anything to reduce weight.
2) Googleplay shows the weight of the apk to download, the properties of the application show the weight of the application after installation.

Answer 2

How to Shrink APK

Answer 3

Maybe just different engines are used? :) In unity hello world will weigh at least 10 meters. If pure android - several times less. Advertising weighs a lot more.