There is no way to verify that the integrity of the submitter, who could be giving wrong information due to malice, incompetence, or as a prank. There's entirely too much trust in crowdsourcing.
Maybe local business organizations can provide help in this, have a few people dedicate some of their time to making sure all listings are correct. Alternatively, counties / local governments could take this responsibility upon them; after all, local governments dislike seeing local businesses go out of business or get less customers because they can't be found on Google.
At the same time, Google could do better in verifying changes; cross-check them with official address books and business registries and the like.
In OpenStreetMap as a community project which is know as such people are much more likely to report things (on the German website there is even a big button for that). It takes longer for a edit to be approved in google map maker than people get easy stuff fixed in OpenStreetMap in my area. If I check my notes RSS feed after 1 week then most of the errors are already fixed.
Edit: +1 Cthulhu_ Google=private company
Once they do, it will have the same problems Google does, but worse because they don't have the resources to fight back.
It is much easier to fix mistakes than it is to fight an active adversary.
(Also, a bit dishonest to call OSM irrelevant when it is the canonical data source for a number of famous application, including Apple, even if it's not directly applicable to the situation here.)
Except that Wikipedia can't manage the problem. See cratermoon's post along similar lines upthread:
but worse because they don't have the resources to fight back.
Google does not come anywhere close to this. Not to mention that only a few of them can actually approve and fix things.
And because google is closed it does not have any kind of Quality Assurance tools. In OSM you could easily check if the last edit changed the opening hours and if the new one is strange (like not open Saturday evening)
Sure, it's unfortunate, and these kind of "crowd-sourcing casualties" are going to happen here and there, but is it really that big of a problem, relative to the value that is gained?
imagine running bobs pizza just paying 100$ to some russian or chinese group to put negative yelp reviews for the near tom's pizza as well as change their opening and closing hours on places like google, etc costing them 10s of thousands of dollars.