In some jurisdictions, there are fire codes which limit the # of people (note people, not adults vs. kids) in various room types.

In those jurisdictions, it's important to correctly state the # of people so that you don't wind up with the Vendome problem above. At some properties, that can be extraordinarily costly at the time of check-in.

Not worth the mess to provide less than accurate information, esp. when it doesn't matter. If 3 people causes an up-charge, call the property and let them fix it.