On a personal level I have never been overly worried about how to best get ketchup out of the bottle. But, I recognize it can be a source of consternation for some, intrigue for others. Thankfully, science has weighed in.
However, before going there I will offer an observation or two.
I have never really liked the inverted bottles shown in the picture tease for the article. Yes, it keeps the ketchup in the "ready" position, but when you finally muster the correct amount of pressure on the "squeeze" it tends to squirt out in a some what uncontrolled manner. I don't like it. Give me the bottle, plastic is fine. I can more easily measure the flow rate.
Second, I have never been able to get my brain around the fact that tomatoes are fruit. I know they are, but they just seem like a vegetable to me. Why does it matter? Because I cannot embrace a bowl of fresh fruit at breakfast containing sliced tomatoes anymore than I can handle the thought of putting pureed fruit on my hamburger or hot dog.
Back to pouring ketchup out of a bottle. A researcher from Australia has put his considerable intellect to work solving the challenge. For me, a simple tap or two with a knife on the side of a glass bottle of ketchup gets the job done, but enjoy the science.