Our code base is growing for 20 years now. We are about 10 devs + sqa working with 500kloc. Some time ago a small team of us (2 devs, one from sqa) started working on an automated test program. Currently one run takes 11h and is somehow an integration test. We are working on it to get this down and reduce false positives and are making good progress in that. But details shouldn't matter.
It is working okay and we continue to improve it. We (the small team) like it very much. If we break something, we notice a day later and not 2 months later when sqa takes a look. Also, our managers (dev + sqa) like the idea. But other people in the team just ignore the testresults. In their mind, if tests are failing after a checkin, it's a problem of the test and not of the code change and it's just our toy project. We had discussions several times if a failing test is a real error. Most times it is.
We can't and don't want to enforce something. How can we show that automated testing is a thing?