> Software works 80-90% of the team exactly as it should.

Either you work in a non-standard field, or your standards for software are way too low.

What software gets to fail 80% of the time? If your ecommerce checkout software fails 1 in 5 times, you don't have an ecommerce business at all, you are dead in the water. If your airline booking software fails for 1 in 5 customers, you are out of business.

99.99% reliability still means 1 in 10000 customers are experiencing an error, which at scale can mean thousands to millions per day. That's completely unacceptable for any software I've ever been involved with writing.