If it's done as a browser extension, the way Keepa is (it's used to monitor price history on amazon.com), there's absolutely nothing the companies can do about it.
Tactics that have been used against similar tools:
- Changing the generated HTML so that the extensions selectors no longer grab the right data (this becomes a cat and mouse game and there’s a non-zero chance that the extension authors tap out, especially if there’s not enough money to sustain the workload)
- Filing nuisance complaints (DMCA is a standard one here, but there are lots of others)
- Filing a copyright lawsuit in court
- Filing other court lawsuits (lost income, slander, etc)
In many cases the business knows they are fighting a losing battle but all they need is more resources, more time, or more patience.
- Changing the generated HTML so that the extensions selectors no longer grab the right data (this becomes a cat and mouse game and there’s a non-zero chance that the extension authors tap out, especially if there’s not enough money to sustain the workload)
- Filing nuisance complaints (DMCA is a standard one here, but there are lots of others)
- Filing a copyright lawsuit in court
- Filing other court lawsuits (lost income, slander, etc)
In many cases the business knows they are fighting a losing battle but all they need is more resources, more time, or more patience.