Hold It

I was just on a plane & it was bizarre to me what I had seen before but had forgotten until this flight. How is it possible that everybody that gets on a plane runs to the restroom five minutes before a flight leaves & then as soon as the seat belt sign goes off & the plane is in the air, they have to make the mad dash to the restroom again? This is crazy enough but even on this flight, which was one & a half hours, as soon as the plane landed, everyone ran to the restrooms again. How is this possible, I can't comprehend it? If airlines were smart, they could offset costs & lower airfares by charging for restroom visits. We then get what we pay for & pay for what we use. Everybody wins except the person that goes to the restroom three times in two hours & if they need to hit the restroom that many times, they need some other type of help. LOL