For example, if an employee does not fix the time at which they have to get to work, an employer does. Now if you have other workers consistently coming to work early, while you're not.
This is relatable, I worked for a company, actually, it was the company I started my Telecoms career with in SA, for 6 years that I worked for the company I was only late to work 1 day.
And that was one of the characteristics that earned me the boss's favorite, for me it was natural not to be late in anything I do, some might see it as a competition while unknowingly could be competing against me, and for me I will be at ease at myself doing what I naturally.
We should always remember that we are unique in way(s) that we will most likely outshine those competing against us.
You're right, sometimes being early to work is some of the right attitude to work we often cultivate that we do not even see as anything. Just like between you and your boss there. However, there are people who are inherent late comers and because of you do things differently to them, they'll see it as a competition. When we're wired to be hardworking and resilient, others might see this at a threat sometimes.