Living in the US (and growing up in humid Houston), line drying was indeed seen as something that you would only do if you were poor. If you put wet laundry on the wash, it'd likely still be damp days later due to the humidity!
Additionally, I had the same experience as iridaceae with apartments and homes in HOA areas that prohibit line-drying laundry.
Now, living in central Europe, our washer/dryer combo is a disaster, and while our landlord also provides a separate dryer, it is so low-powered that once I timed how long it took to dry a pair of jeans constantly in the dryer - it was 9 hours. That's ridiculous. So I bought a drying rack from IKEA that can hold something like 25 items, and I do laundry just before bed and put the items on the rack. In the morning, they're 95% dry, and I just toss them in the dryer for 15 minutes to get out the stiffness and that last bit of moisture.
Now that I've had that experience, I will definitely be doing the same when we return to the US, because I've noticed that the clothes just hold up better when they don't spend as much time in the dryer. It will have to be inside, though, because we will still have those same humidity issues.
A question for those who do line dry outside - doesn't it smell bad or get dirt or bird droppings on it? Whenever I've been outside there's sort of an undefinable "outside" smell that clings to my clothes, and we have so many birds and squirrels in our backyard in Texas that I wouldn't trust leaving my clothes out there, even if it were permitted by the HOA.