What do toilet seat covers actually do?

In my travels I have noticed that places outside of the US and even some areas of the US don’t have toilet seat covers in public restrooms.
Though I do have to say that many years ago I was at a truck stop in Germany and they had this amazing self-cleaning toilet. It was the cleanest public toilet I have ever used.
I like to use toilet seat covers. But are they really necessary?
From a HuffPost article … Those liners may have more to do with providing comfort and reassurance to the user than actually doing anything to prevent disease, says infectious disease specialist Dr. William Schaffner, M.D., a professor of preventive medicine at the Vanderbilt University Medical Center.
Someone recently told me if there is no toilet seat cover just hover over the toilet seat.
When you hover your muscles are tense and you can’t completely empty your bladder.
There is actually a WikiHow article teaching you how to urinate. Wow!
But back to the hovering, here’s what WikiHow says: Do not “hover” over the toilet seat since doing so tenses the pelvic muscles. When sitting on the toilet, you should sit completely and keep your feet supported so that the pelvic muscles can relax. Your legs and knees should ease apart comfortably and should not be pressed together.
From BJOG: An International Journal of Onstetric and Gynaecology, a study on British women found that while hovering there was a 21% reduction in average urine flow rate.
From Today Health, the bacteria often found on toilet seats are common skin microbes that most people already have, so they pose little risk according to experts.
Pretty much everything has more germs than a toilet seat. The Wire has a list of stuff that has more germs than a toilet seat. You may or may not want to read it.
But here are a few things The Wire lists that we use on a very regular basis:

• Steering wheels have 9 times more germs than a toilet seat.
  
• A computer keyboard has 5 times more germs than a toilet seat.
  
• A desk has 400 times more germs than a toilet seat.
  
• An iPhone has 18 times more germs than a toilet seat.
  
  

Putting my butt on a toilet that hundreds of others have still seems gross. Even with these facts I will probably still use the seat covers because it makes me feel better.
I try to regularly use Lysol/Clorox wipes to clean my iPhone and keyboard. I even have wipes in the car for the steering wheel.
Our best defense is to wash our hands regularly.