WordPress is definitely loved all over the world, in US not more or less than in other countries. Of course there will be some statistical differences, you might find some country related statistic if you google around, no idea.
And your second question, guess what - everyone loves free shit even if they are rich proud US citizens.
Not only in US but most of the bloggers from different countries prefer WordPress due to many advantages. Now when it comes to using free or paid resources that depends on the webmaster. About 12% of the total Websites you see over the Web is Powered by WordPress. It depends upon the choice. But WordPress is the best Blog tool all over the Web. Easy to use, Reliable, Easy Access. Only you need is to Pay for Hosting Service.
For the last 2 years WordPress has become more than just a blog platform. It is used for any kind of web projects today. More than 60% of all sites that use a content management system are powered by WordPress now.
I've tested Wordpress with a project site just to see how it worked before I started actually setting up sites to direct traffic to. I liked it well enough. Probably would've liked it more if I had used some of the paid features.
The best answer so far for the side of your users OP. Just like to add, if you are asking what will you use & don't have a single Idea about CMS.
Wordpress has the best and has the shortest learning curve. Also the same reason why most are using wordpress because the basics can be learned in a day compared to other CMS.
But yes your Users couldn't care less whatever CMS you are using. Its all about your presentation.