Why is country music stereotypically synonymous with trucking?

Ok, I'll throw in my two cents. I'm no expert by any means but since I've dabbled in music throughout most of my adult life, I'll take a shot at an opinion in this thread.

1st, I got into live radio in 1982... country music in a small market radio station. I played that for a few years then went into the club scene where we played mainly oldies rock & roll, then advanced into some current pop in the late 80's - early 90's. In 2002, my wife & I started a mobile DJ service playing weddings, birthdays etc events for 17 years until 2019. All of these music related jobs were part time gigs.

In my opinion, truck driving has always been a blue collar job. Up until the last 20 years, its mainly been ol' country boys & the likes. I'm not taking away anything from the educated city folk who drive a big truck but trucking has mostly always been blue collar, hard working, hands on kinda people.... mostly (especially pre-2000), hands on, country boys. Country music has always been the staple for truck driving back to the days of Hank Snow, then Red Sovine & Merle Haggard. Then Alan Jackson came along. We could go on & on with lists of artists and songs related to truck driving but truck driving songs were really no different than Moe Bandy or George Strait was to rodeoing..... or like Johnny Duncan was to cheating songs. It was just a style that some writers & artists followed.
In the end, I think it was just a lifestyle/industry that songwriters followed up on that a LOT of people related to. Trucking was an industry that everyone witnessed whether they were involved with it or not. It just touched base with a lot of people. Trucking was a reality for some people... a dream for others. So, a lot of people could relate... & live out &/or dream about the trucking life, living on the road & seeing the country. Songwriters & artists capitalized on it.

But trucking has always been more closely related to country music because that's who most truck drivers have been throughout the years (with some exceptions of course). Just plain ol' hands on, hard working, blue collar country boys just trying to make a living the hard old fashion way.
In the end, I dont think the connection between trucking & country music has changed over the years as a whole... I think its the people & the lifestyles that has changed in the trucking industry. For the most part, trucking & country music is still hand in hand.

(As a foot note I'll say that I listen to a variety of music, as I grew up on a variety of music. 60's - 90's country, classic rock & pop are the mix that I listen to.)