It's not dependent on any centralized authority. Anyone can make them and anyone can accept them. They're negotiable. If I give you .15 bit coin you have .15 bitcoin. If I gave you a check for .15 dollars you have a check for
.15 dollars. Both are trustless as you say.

The only difference is that you want to think of check as having to be converted into cash and therefore unreliable. That's a psychological issue, not a check issue.