anybody can edit anything. I would be very surprised if our politicians weren't doing the same thing to their entries.
Yes, anyone can edit anything but there's a history published as to who does what and when along with the content, and, there are dedicated volunteers on behalf of the site that pour over all content, eventually, and correct anything that to their view is "biased" or even irregular.
Of course, you then have to contend with the bias of the volunteers themselves, so that's another story.