Also it is a tax credit.. meaning you only get the $7,500 if you actually owe at least $7,5000.. AFTER the standard deduction. Basically, anyone with under ~$100k annual income would not even receive the whole credit, if any at all.
http://www.taxpolicycenter.org/briefing-book/whats-differenc...
So setting aside whether this is fair or unfair, people that owe more taxes clearly get a bigger benefit from the credit.
https://www.irs.gov/pub/irs-pdf/f1040.pdf
But lots of people don't end up paying $7500 in income taxes.
Also, you don't need to take it all one year. Tax credits carry forward up to 10 years.[1]
[1] Disclaimer, I am not an accountant