It's more common than you think, a lot of long distance links between cities are a varied combination of aerial, direct buried trenched armored fiber, underground fiber in ducts.

There are also a lot of long-distance links carrying DWDM traffic that are >95% aerial, not on poles that can get hit by trucks, with singlemode fiber inside high voltage AC transmission lines (https://3ee2108sdg.files.wordpress.com/2014/07/cropped-20140...).

I do fiber runs and whenever possible it is strung up on poles. It is far faster and easier than doing underground cabling because there are no utilities or gas lines or what have you to possibly hit. More of the stuff put down 15 years ago was put underground but a lot of it now is just lashed around current telephone lines.