How do you think google maps got such a good database of these things? When I last used it, Google maps used to actively ask you for this sort of information.
The shop owners also put their hours onto Google Maps, or paid somebody to do it. You shouldn't labour for free for Google either.
Even if you managed to help a shop get hundreds or thousands of new customers by updating their online information, they wouldn't even give you a cup of coffee if you asked. More likely they'd spit in your face.
For most physical businesses that are open to the public, correct information on map services are by far their most important advertising. Yet, they neglect this and spend thousands on billboards, social media, radio spots, etc. If they are failing as business owners, that's their own problem.
I think they even robocall stores with something similar to Assistant to check if they're open on holidays, which is definitely something that would be difficult for a smaller or community-run database to accomplish at scale