(Polygon 2D) Collider not working as expected

I started with Udemy courses. I completed them but I am still studying Unity on my own. I recently downloaded the latest Unity LTS and started following another simple but comprehensive Unity tutorial (youtube). I was following the portion on collider and I'm supposed to use polygon collider and I now noticed that whilst it is computerized to follow the shape, 95% is accurate but I can't seem to customize the remaining 5%. I tried it a few times and it's troublesome as the collider just refuses to follow the shape 100%. I hope that this post can be supported by being voted so Unity developers can take note of this and change this. I'm not sure anyone everyone has this same problem but to me this is a problem.