Probably because the writer is not reporting her own original research. She is reporting work done by others, they often used metric, and any metric units were converted to common US units because the article was intended for a general American audience.
And why isn’t there a button to restore the original metric units? Same reason why when a newspaper reports a translated quote from Macron or Putin or Xi, there is usually no button to restore the original French or Russian or Chinese: the editor decided that it wasn’t necessary for the intended audience.