Did you click on the pages there? If so, you'd have seen the message:
"Sorry, we are not able to license media #511436671 due to country, company and/or publication restrictions."
All iStock pics are available to a subset of Getty contributors under the Getty Plus (previously Getty 360) scheme.
If you are not a G+ buyer you see the 'not able to license' message.
Why they don't have a link to iS where you can buy it is one of Getty's unfathomable mysteries.
If you sell a licence via G+, it could be from a few cents to decent numbers of dollars, and will show up mossy green on your stats chart, like PP. Usually PP comes in first, then image subs (grey bars) then Getty and G+.