“Was interested to learn that they were able to hold “second jobs” for which they were paid, and that they were able to save that money, sometimes even enough to buy their freedom.”
What was their first job?
Jefferson was very enthusiastic about peas. So, probably something to do with that. That and the big silo of river ice he kept in his basement.
It is a lot smaller than expected, and many of his ballyhooed features come across as a tad silly when seen first hand.
Almost every plantation had a great need for skilled tradesmen and women, and they ran what would today be considered subsidiary buinesses, such as the fishery at Mount Vernon that was a large exporter of dried fish to England, and the nail factory at Monticello that supplied much of southern Virginia. Women excelled at textile manufacture, among other trades. Skilled persons had the leverage to bargain for privileges, such as being the ones to accompany an overseer to another town to handle distribution or find new customers. They made contacts in these overnight excursions all along the way. A skilled worker such as a nailmaker, a ceramicist, a brickmaker, a boatsmith, etc, could be loaned out to another plantation or farm to "transfer technology" and would have found the recognition ego-rewarding as well as remunerative.
The Bible mentions by name quite a few artisans from 5,000 years ago who built the Tabernacle and Solomon's Temple. Likewise, many of the plantation artisans supported by Washington, Jefferson and other Founders also are known by name and recognized on these tours.
Before women's liberation, most women were supported by men and worked in home-based trades and crafts as well as raising children. It's not much different from the condition of the skilled workers on plantations -- room, board, clothing, heating, materials, tools and creative opportunities all supplied by their patron. Life could have been worse.