What you say sounds right, but it's not. Using some DB APIs you'll get back a list of results, and you'll know from the SQL that it will only have one result.
Another example is if you know there is a single item in a data structure, and use list comprehension to extract it. You'll end up with a list of one item.
Another example is if you know there is a single item in a data structure, and use list comprehension to extract it. You'll end up with a list of one item.
These situations happen, and for good reasons.