I mean I would "like" too, however, working in a startup there are some limitations. Our primary focus is building software that will improve metrics for our business, often time that software will only last a few months or so. As a result, it's just too costly for us to write tests for code that will only last a couple months most likely. Again, we would like to, and there are certainly some parts (small-parts) that have lasted for more than a few months and those don't have tests either, in that case, we "just never got around to it".