Weird SQL code: Why do they use a subquery instead of join?

Question

I met the following MySQL code:

SELECT ServiceFee
FROM Shows
WHERE ID = (SELECT ShowID FROM Orders WHERE ID = ?)

It makes me wonder because the people who wrote this code usually use SQL joins. I would rewrite it

SELECT ServiceFee
FROM Shows
INNER JOIN Orders ON Shows.ID = Orders.ShowID
WHERE Orders.ID = ?

My question: Is there any reason why this code was written with a subquery and whether it is completely safe (producing the same result in all situations) to rewrite it with the join?

Are there any caveats?

Answer 1

"Is there any reason why this code was written with a subquery"

a very long time ago MySQL joins used to be slow