Search "American inventors" with the quotes and you'll get what you're looking for. Without the quotes you have to assess each word individually and with order independence. The "American" portion of the search phrase will result in a higher connected relevancy for "American inventors" who are also "African American" due to their shared keyword space. This is also probably why you're not seeing similar results when trying to repeat the experiment for other countries.
The issue is that some web applications don't load what traditionally were discrete pages (e.g. PAJAX) with their own URLs. It's a trend you'll find in sites built to feel more like applications. Scroll the the bottom of an onion.com article and watch your URL update to the next page without a page refresh. This was done so modern sites built like this could still allow the user to navigate back and forward. It let's the site update the browsers location history and effectively what URL that back button will point to. I could imagine blocking this behavior if it points to a site off the TLD and it's sub domains. Hard pressed to figure out how they could prevent this, definitely a flaw in the trust model but probably worth the trade off.
Probably not the answer you're looking for, but our small company, of 7 full timers and a handful of part timers, switched to Gusto for payroll about a year ago. I know our founder who had previously managed all this himself has saved himself a ton of time and stress. He's generally a frugal person, so if he was won over it's probably worth a look. Since then I've know a few other agencies who have switched to Gusto as well. From an employees perspective I have to say it's been great. I get emails when I get paid, I can easily grab my paystubs, and access to my W-2 without and issue.