I thought Let's Encrypt with ACME did this. What's the 20% you talk about. I'm interested.
- Appliances that have no scripting API and force you to install a certificate in the GUI (I have a lot of these)
- Some Microsoft services that will only take a new certificate after a restart, causing downtime. You can automate it, but not every 90 days without upsetting people.
- Political issues