"A surprising statistic is that "like last year, about 30 per cent of developers still don't have unit tests in their projects", or so the survey said."
I don't think that's terribly surprising, personally. It's in line with my personal observations, and am struggling to get the dev team I work on to start implementing unit tests.
I think the main reason for that is that the quality and productivity benefits from unit tests are all at the back end. At the front end, unit tests look and feel like a time-sucking pain in the ass that makes hitting your deadlines more difficult. This is made worse by unit test extremists who tend to be obnoxious and insist on things that don't make practical sense (such as that every line of code should be exercised through unit testing).