Is There a Conflict of Interest Clause in Contracts?

As a former HR professional, I would be shocked if any company here allows dual employment on full-time employment and doesn't have conflict of interest clauses. If you don't like the terms quit or negotiate a fixed term equivalent contract - not whining about how time consuming and fruitful it would be. Yes, different types of contracts should be available but if there's talent supply for those who agree to standard terms why would companies make the effort?