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.
When I'm teaching about the Commandments, I use "Thou shalt not covet thy neighbor's wife" to illuminate the remainder. That is, "your neighbor's wife" is obviously a specific person for whom your neighbor has a specific claim. In the same way, "your neighbor's lawn tractor" is just that, not a similar lawn tractor that you could buy for yourself at Home Depot.