Training for Free
Very many if not all flight schools offer a scenic/tour/experience/introductory flight in a general aviation aircraft such as a Cessna for the specific purpose of knowing if you want to seriously pick up flying, but I doubt you can convince them to do it for free - possibly they might give it at a discount when you sign up for a full course.
Otherwise there are many facilities nowadays which offer to test a full-scale simulator. Here again, it will cost a bit but you'll probably be a good deal of fun.
The 'problem' is that aircraft are prohibitively expensive to ride on for free - you're often looking at $100+ an hour with an instructor, who you can't go without. In Europe, there's a good chance you're looking at €150 or so for the same, but these are just estimates. It's an awful lot more expensive than cars.
But if you're serious about spending several thousand dollars for a license, it won't hurt to get up a little before you commit yourself fully, and even paying the cost of a flight will be tiny if not insignificant compared to the future training cost.
I certainly agree with you that there's a lot of information online, but it doesn't substitute learning to understand the aircraft, and there's no substitute to the real world. The FAA says you need at least 40 hours of flying, along with a list of other requirements to get your license.