There's a bit of hypocrisy out there on this subject among Traditional Catholics. I've known Traditional Catholics who have no problem going out to eat or to a place of amusement on Sunday ... and at the same time they'll make derogatory comments about the people who work there. It's one or the other.
It's clear that NECESSARY work can be done on Sunday. So, for instance, preparing a meal, even a labor-intensive one. If follows from this that it's permitted for people to work at a place which provides necessary services ... restaurant, hospital, gas station, drug store, etc. Some people think it has to do with money, but it does not. If I ask someone else to do the work of preparing a meal for me, then I am required in justice to compensate them somehow for this, i.e. pay them.
Now, the people who work there should have proportionate reason for doing so ... e.g. it's very important to them to make ends meet for their family. Or, they're required to take rotations for working on Sundays as part of their overall job requirements. Alternatively, we could try to dump this work on a Catholic equivalent of the "Sabbath goy," i.e. have infidels (Indians, Muslims, pagans, etc.) do this work. But I wouldn't want to go the route of the Jews on this one.
With that said, it's important to minimize the work done even in support of necessary things. So, for instance, if I need gas on a Sunday (I'm not always bright enough to plan ahead), I make a point of going to a self-pay pump. Or if i need groceries, I try to use the self-checkout lanes (which are very common these days) ... in order to minimize the level of effort required to serve my needs. Ideally, we would tank up our cars and buy groceries the day or two before Sunday so this is not necessary.
What's at issue is the work allowed in support of a PERMITTED activity, such as amusement. Can I go to an amusement park, where people are being paid to work in support of this activity? I personally lean against this, but some theologians and priests hold the opposite view. So, for instance, they'll say I can go to a Sporting Goods store and pick up sports equipment required for my amusement that day. Can I go to a baseball game where people are working to make it possible? I lean against this myself.
It's certainly gravely immoral to go to a store that provides services that are neither permitted nor necessary on a Sunday. So, for instance, let me go car-shopping at a car dealership. Rare is the case where you immediately need to have a car on a Sunday and you can't wait til Monday. If you need to get somewhere, you could get a ride or call a cab. Should I go get an oil change on my car? Absolutely not. Can a Home Improvement store be open on Sunday? Not for the most part. But what if someone's thermostat breaks in their home and they're freezing in there and need to get a new one? I had that happen once on Christmas Day, actually, and went to a drug store that happened to have some.
Now, one can make an argument for trying to be perfect. Get everything you need for your necessary and permitted activities beforehand ... and spend a day or two freezing instead of replacing the thermostat ... but there's a fine line between trying to perfectly follow God's intentions with the law and becoming Pharisaical about it.