What's with those "football stadium", "tennis court", etc measurement units?
Is it assumed that everyone knows how much that is? Are they more understandable than giving a number (area) or two (length x width) in SI - or even Imperial - units?
Instead you have to go search for what the size in that particular sport is, so you can get any idea of what they're talking about!
Does it really make a difference if it's 45x45 or 53x50? If you're trying to imagine roughly what it looks like, no. Their point is that the thing is close to something you could reasonably sort of picture.
I couldn't be less interested in tennis, but I've seen what they're describing at my local park.
Maybe they remember the area of their house and that will give them some idea (it is around 9 times the area of my house).
Most people will have a decent idea of the size of a tennis court. Their school likely had one that they would have seen when taking physical education, even if they never actually played. They also show up in movies and TV shows.
Same goes for basketball courts and football fields. They are probably actually better than tennis courts for this because basketball and football are more likely to be televised.