You’re right and that’s because there is no clear cut answer.
God always looks at the heart of the person. The priest in post no. 2 couldn’t possibly know the heart of the man cutting the grass on a Sunday.
The commandment is to keep holy the Lord’s day. One could be cutting the grass and NOT keeping the Lord’s day holy because all he’s going to do all day is work and not spend time with either God or his family.
Another person could be cutting the grass, for reasons given by other posters above, and then plan to spend time with his family, his God and devote the day to keeping it “holy”.
It’s always the heart.