Why is it that when people cite a link to support their point, they can't even manage to read it properly?

Your link says 21.8 millions for Delhi metro (as your quote specifies it). A figure that is dated from 2011. At that time, according to your other link, Texas was somewhere around 25.6 millions.

So, Delhi metro population was about 85% of Texas. Given the comparative growths, this percentage has probably raised a bit during the last 5 years. Overall "almost" looks to me as a correct approximation.