Developers are either forced to track their time, or their time is tracked for then by the company for a very practical, but stupid reason: taxes. There are R&D tax credits, at least in the US, that require a breakdown of developer time. There are consulting companies that spend their time preparing these reports for startups and larger companies. It's serious and stupid. At least in many cases, these reports are not used to micromanage, they exist to get free money.
