It’s public information that’s not copyrightable. Imagine the price of potatoes at the local grocery store/chain being proprietary information! 
FWIW, copyright and license are 2 different aspects.
Hmmm… Not sure it is,
as access is subject to restrictions on what all one can subsequently do with it.
For example NSE - NSE Data Sharing & Usage Policy - NSE India
Exactly, the data/quote itself is not copyrightable. Hence if someone hasn’t signed a contract for a licensed official NSE datafeed, they’re not bound by their TnC. 
I can maintain my own database of quotes from public sources and license/disseminate it however I wish. 
Personal opinion: companies gatekeeping public info for a few pennies are scum. 
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Personal preferences aside,
do remember to review the terms and conditions of accessing such data from each of the sources. Something available on some website on the internet withh/without a login or payment does not automatically make it public domain information. They almost always prohibit reselling the info.
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Enforcement matters. If you can’t enforce your license terms it’s useless. Also just because it is in the license does not mean it’s automatically binding or the law. A good lawyer can easily poke multiple holes to make it invalid. After that politics and optics including public opinion do play a role even in courts.
hey, I recently got hands on NSE tick data. let me know if you’re interested connect me on [email protected]