Ask HN: What was the last 'easy' thing you did, and why was it hard?

Many years ago, I worked with a guy who was fond of saying "If it were easy, they'd hire high school kids to do it." I realized that the corollary was "And they'd pay them minimum wage."

The stuff we do is hard. Even the "easy" stuff is often hard. Don't expect that "easy" means it's easy.

That's kind of the spirit of this question. Things like dates are really hard, but because we use them every day they seem 'easy'

A robot that would navigate my little workshop. The idea was simple: just have it use some sensors to map the room and items located on the floor. It all started very simple but grew complicated when the layout and type if things located on the floor changed. At one instance I had a stack of one gallon water containers. It confused the simple robot into a little cute side-to-side dance because it could not figure out what to do. I tried to solve that problem but realized that it would require more hardware than I thought (specially a lidar). The robot was dismantled to build others.

Pretty much any multi-threaded application always seems to belie its true complexity