Why did Britney tank on radio?

[mariahperry]

Why did Britney underperform on US radio so much?

Britney is undoubtedly one of the biggest popstars of all time, but for whatever reason(s), US radios never seemed to warm up to her so much. FYI: I’m well aware of the radio blacklisting and how it affected her single performances. But what befuddles me even more is the performance of her pre- & post-blacklisted singles on the Billboard Radio Songs chart.
 

According thereto, Britney Spears never had a #1 hit on US radio. Baby One More Time peaked at #8 (?!?), as did Oops. In fact, none of her pre-blacklist singles even reached the top 5 on US radio, and just two of her post-blacklist singles. Till the World Ends and Scream & Shout (which isnt even her song). 
 

Does anyone have any explanation/speculation about why this was? I’d be grateful.