It's because people on the right keep redefining the names.
The "liberals=communists" canard means liberals are reluctant to use the name anymore. So liberals have reached back into their history to find a synonym.
"Progressive" is the name of the movement at the turn of the last century that started all the regulatory mess: demanding humane care for the mentally ill, regulation of the meatpacking industry, etc. Horrible stuff.
They also made the mistake of being behind Prohibition because of their earlier commitment to the Temperance Movement (the 19th/early 20th century version of the War on Drugs), but that's what comes of outlawing a health problem. Hopefully we have learned from this.
It's only a new term for people who have never come across it before.
Regards--
Mary Anne
Off Topic » in reply to Canada
Name calling