I'm sure Google/Apple know about this and have the measures to detect it. It's as easy as see the location of the IP from which they installed or a lot of other parameters they track.
What surprises me is that they allow this since it's totally unfair to developers like me and my girlfriend that make a great effort in the time free of work to make those apps...
Installs mean the total number of installs in the whole lifetime of the app. Also it doesn't matter the device. What counts is the google account. So every install = 1 google account registered in Google Play Store. Also google requires to verify the account with an sms these days.
These days is harder to create a google account since you need to make the sms verification process. That's now a requirement to be able to login to Google Play Store.
The installs count since the moment you pressed install button. They don't decrease when people uninstall. However the uninstalls are visible in developer dashboard.
Apart from that, I continue monitoring, and the numbers of ratings keep growing. Also I noticed something strange when you refresh a couple of times the play store page. https://media.giphy.com/media/3ohryBbqtYeAkomS3u/giphy.gif
It appears to be two different counts of ratings? Crazy...
From our experience as publishers and creators of these apps: https://play.google.com/store/apps/dev?id=548828401423122855... I know that the delay is max. one day. Both for rating and installs. I'm sure that the numbers you see in the store now, are from yesterday, but still they don't match.
I use Time Out app for OS X. Spend some time reading articles about this topic and you'll understand that the most important is to take breaks and avoid long hours in same position. I set it up to lock my screen with postpone button for normal breaks and no button at all for micro breaks. Normal breaks are 2min every 2h and micro 20sec every 30min-1h. While on break I try to move eyes in different directions which is like going to eye gym :D
What surprises me is that they allow this since it's totally unfair to developers like me and my girlfriend that make a great effort in the time free of work to make those apps...