When you are comparing online job boards to employment centres and classifieds, they are more accessible and available. Employment centres always involved making a dedicated trip. Newspapers cost money and may involve a dedicated trip to fetch one. Not to mention that plenty of businesses simply didn't advertise jobs in print, particularly entry level jobs. Part of that may have been expectations: people would actually walk into businesses to drop off applications or see if openings are available. Again, it took a lot more effort to find those jobs.

Fun tidbit, I remember visiting Edmonton (Alberta, Canada) in the early 2010's. Boom times for them. It was a bit like walking into a different era with respect to job seeking since many business (again, entry level jobs) were advertising with help wanted signs in their windows.

There was a "Job Spotter" app in the late 2010s where you would take pictures of help wanted signs and get paid small amounts, a weird bridge between online job boards and physical signs. I made $50 in five months, then the pandemic killed it. During our lunch hour, my coworkers and I would race to each storefront to see who could get their submission first.

https://theamericangenius.com/app-pays-snapping-pics-help-wa...