I don’t agree. You want 3 months notice for yourself but not prepared to reciprocate with the same contract terms for your employer, then you want to have your cake and eat it.
You’re assuming that an employer and an employee are on equal standing. Fact is that, broadly, it’s a buyer’s market. Generally speaking, for a regular job position, it’s harder to find a job than it is to find a replacement employee.
Sure, if you’re a CEO or something then it’s a different situation, but on the whole supply outstrips demand. Who would be hardest hit, a company losing an employee or an employee losing their job?