As you advance to higher levels your reporting permissions grow, as your reports get greater influence on real-time routing. This is tracked in the Waze client application as can be seen in the Scoreboard.
To reach Royalty level (crown icon), you have to be in the top percentage of all Wazers in your locality (in the US, this is determined by state).
The top percentage is calculated once a month, and if more and more Wazers get points, it's possible that the total amount needed to reach shield / sword / crown will actually go up.
While it could be frustrating, it helps guarantee that no one gets the 'Waze Royalty' level for good. It always gives a chance for new Wazers to come along and get it.