I have a Polaroid tablet. It does not have Google Play. I called Cust. Svc, they don't know why. I know that Play is closed source, but still free. Other Polaroid tablets do have Play. Why on Earth would a company make a tablet that does not feature Google Play?
The answer is most likely that your Polaroid tablet isn't licensed to use Google Play. There are a number of requirements that must be met before Google licenses its app store for use on a tablet. Some of it has to do with software compatibility tests that pass or fail for the device.
This is from the Polaroid tablet FAQ:
It says: "Our tablets are not licenced with GooglePlay store as of yet..."
I'm not sure how old that FAQ message is, though, as it goes on to suggest that tablets don't need Google Play but smart phones do. Weird. It also says that you can use Amazon's app store.
There's also this link which goes over how to install Google Play on a Polaroid tablet. I don't know how good it is, but it might work for you...
I'm not sure why any Android device manufacturer wouldn't include Google Play. My guess is it requires a fee to license it from Google. But supposedly it costs nothing to run their open source compatibility test to prove their devices are compatible with Google Play. There may also be other legal issues, especially with regards to different regions, content distribution and encryption.