@galaxy_map @chiraag
To a lot of the people publishing papers in these journals the paywalls are invisible. They work at universities and the like that pay extortionate institutional subscription fees to the publishers to obtain unlimited access for computers connected to the university network. They know that the paywalls exist, of course, and should care more about them, but they're not confronted with them on a regular basis.
Second, people did figure out a workaround: "pre-print" servers such as https://arxiv.org have been around a long time. Usage varies by field, but in astronomy at least most papers get uploaded to the arXiv prior to official publication where they can be accessed for free. A secondary benefit of widespread use of services like arXiv is that it matters less which journal you publish a paper in; if most readers are discovering papers through arXiv it doesn't make much difference how much traffic the journal's website gets.
More recently a number of free, open access journals have been created that use the arXiv infrastructure as their back end, e.g. The Open Journal of Astrophysics is an arXiv overlay journal that is free not just to read, but to publish in too.
That last point is important. One of the things that can hold authors back from publishing in open access journals is that they normally charge higher publishing fees than journals that charge readers for access. The administrators that hold the purse strings may not approve payment of these higher fees.