“Thou shalt not covet thy neighbor’s (direct object).”
It’s not really the sin of covetousness unless you want someone else’s Cadillac, as opposed to buying your own.
You’re right. Coveting is very misunderstood. For example, to see my friend have a good, supportive wife and think “He’s lucky, I’d like a wife like her,” isn’t coveting. Indeed it may be good judgment.
It’s only when one thinks “I want my friend’s good, supportive wife” does it become covetous (the desire for the specific object or person). And I think it’s easy to see why - that kind of thinking leads to even more sin, invariably.