Why Avast Free has so many false detections?

Why Avast Free has so many false detections?

do you have examples?

You might want to be more descriptive, what false detections are you talking about?

When I surfed, Avast alarmed me very often on safe websites. After that I made the decision to uninstall it.

When I surfed, Avast alarmed me very often on safe websites.
There are NO 100% safe websites on the net ... safe today can be hacked tomorrow

Every 3.6 seconds a website is infected http://www.scmagazine.com/every-36-seconds-a-website-is-infected/article/140414/
Infected ad networks hit popular websites https://blog.avast.com/2015/08/20/infected-ad-networks-hit-popular-websites/
Malvertising Hits DailyMotion, Serves Up Angler EK https://blog.malwarebytes.org/malvertising-2/2015/12/malvertising-hits-dailymotion-serves-up-angler-ek/

Sucuri blog
https://blog.sucuri.net/category/website-security/website-attacks
https://blog.sucuri.net/category/website-infections/hacked

What part of avast was giving the alerts ?

web-module

Webshield, AOS, Webrep ?

don’t know, i used russian version