Feel free to break it down for us, since I'm not planning on hunting down the original post on X to wade through dozens of replies. Nova's probably right, at least; the five-day work week wasn't established as the norm until the 20th century. And given that Scrooge was a moneylender, it wouldn't surprise me if contemporary readers would have inferred that he was Jewish and kept his business open seven days a week, only closing for Christmas because Cratchitt convinced him he wouldn't be getting customers anyway.
Adjusted for raw inflation he is making something like $155 a week. The number provided in the various meme posts going around is adjusted for inflation, and then ran through a "buying power" or "labor value" conversion that is of questionable accuracy in the short term, and near worthless for jumping that far back.
He is established to be working much more than a 5 day a week 40 hour work week. At least 60 plus hours, and working a career that should (and does) pay more than minimum wage or its old time equivalent.
His established pay is above average for the time frame, but still well below modern minimum wage.
He is trying to support 7 people on this salary. Expecting to be able to support a family of 7, with one having a terminal illness, on a single salary (if I recall correctly I think his wife and oldest kid may make small contributions to the income as well) is poor family planning.
Scrooge doesn't pay Cratchit poorly. He pays him poorly for what he does, treats him poorly and provides poor working conditions.
Most people who are "capitalism bad!", much like most people that are "socialism bad!" Don't have more than a surface level grasp on the system and don't care to look into it any more to have an educated opinion on it. Its frustrating.