For a specific example, consider some complicated arithmetic expression involving a dozen numbers and repeated operations +/-/*/÷. A person who knows high school algebra, could introduce some structure in the expression (e.g. by defining variables), then use the rules of algebra to simplify the expression, and end up doing much arithmetic overall to compute the answer.
The more (as in abstraction and modelling) math you know, the less math (as in arithmetic) you'll have to do!
Even some of your examples I'm not convinced are lazy according to your own definition. Am I lazy for flicking a switch at ankle level with my toes if I can do it well enough, when bending down would take so much more effort? I think by your standard I should be commended for my foot dexterity! When does the desire to reduce effort cease to be vicious and become virtuous?
... Who thinks that? Is it the same people that think pre-marital sex is a vice?
Edit: Sorry, I think maybe you are asking why HN doesn't enforce article URL uniqueness - I can't answer that.
Yes. The system here normally seems to check uniqueness.
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...