No plumbers don't charge sales tax on services; neither do doctors, lawyers, dentists, or landscapers. Sensible states tax things they want to discourage like gasoline use or smoking. They don't tax people trying work more.
Here in Ontario it's much simpler (but steeper) - the harmonized provincial/federal sales and service tax is 13% on everything. Sales, service, you don't have to give a crap. There's a short list of exemptions for groceries and medical stuff.
Our taxes are high, but straightforward.
Every store in MA has their own opinion about what foods are taxed and what aren't. Candy-yes, gum-no, ice cream at a grocery store - no. Ice cream in a cone - yes.
In some states groceries are exempt from sales tax, but restaurant food is not exempted by any state (except in the trivial sense in states that don't have a sales tax at all).
Federal tax is 5% and provincial tax ranges from 0 to 10%, meaning you pay 5-15% depending on your location for each good or service rendered. Essential goods/services (defined by each province and the federal gov.) are not subject to the specific tax (e.g. in Quebec, books are considered essential goods by the province, but not by the federal, so you pay only 5% tax)
There is something called "exempt capital improvements" and they do not get taxed. Basically, new kitchen remodel doesn't get taxed, but fixing a broken faucet does. Repair a cracked bathtub? Taxed. Rip it out and remodel the bathroom? No tax.