What started out as a little facetious in my own head leads me now to a serious question. Is there some meaningful reason why Google has to use a subsection of images for reCAPTCHA? I really dislike having to do this and at the very least would appreciate some variation.

• Traffic Lights
• Buses
• Bicycles
• Cars
• Crosswalks

Is there something special about these things in this context? Is the visual noise they're usually associated with what makes them good candidates? Are Google just really into urban planning? Who knows...I'm hoping some Tilder smarter than I can help me out.