Why a similar listing was free and mine is not

The category sets the fee, not you and not the other seller. Two listings that look alike can cost different amounts because they are filed in different places.

The usual explanation

A drill posted under Home Improvement is free. "Handyman, will drill and mount anything" is a service, so it goes under Services and costs $5. A room advertised under Property is $3. The same room advertised as a short-stay let goes under Stays and is also $3. Your own car is free; the identical car from the dealer two listings down is $3.

None of that is about who is asking. Swap the two sellers over and the prices swap with the categories, not with the people.

The one exception

Vehicles, and only Vehicles, also looks at whether you are a private owner or a dealer. Everywhere else the answer would not change the price, so you are never asked.

Check the category you picked

Open /post and watch the cost line on the details step while you change the category. If you are posting a general goods item and the line is asking for money, the category is wrong, and changing it there costs nothing.

If it is already live

The composer sets the category and the edit form does not offer a control to change it, so a published listing stays in the category you chose. Everything else can be edited from My listings. To move a listing to a different top-level category you have to post it again, and a fee already paid is not returned for that (see Fees, Payments, and Refunds in the Terms). If you believe a charge was a genuine error, write to legal@jinu.app.