If only your "Exhibit A" wasn't mostly selective golden memory tinted by rose colored glasses. The "great uplift" was indeed (mostly) great - if you were a white collar worker in the city, or an industrial worker with a union. For the laborers down on the farm, the topic of discussion, not so much.
Pretty sure it was proportionally at least as good - probably better - for unskilled labour.
And even then the "great uplift" wasn't powered by smaller profit margins or worker's rights - it was powered by rising salaries, employment, and consumer spending. (Emphasis on the last.) It couldn't last, and it didn't.
You need strong worker's rights for (sustained and economy-wide) rising salaries, secure employment and, consequently, high consumer spending.