Lead Gen Form for Seniors: Guidelines & Close up of AARP Registration Form Design

I'm a big believer of studying the form designs of industry leaders.
When it comes to designing forms for seniors, I think AARP's got in it the bag.

 

Preventing Users for clicking the confirmation button twice:

Error Validation:

Page 2:

 

Guidelines for Designing Forms for Seniors:

General:

• Form Field Labels: Right Aligned
• Form Fields: Fixed width, Single Columns
• Submit buttons: Right Aligned

Address possible vision impairments:

• Large font
• high contrast coloring
• See more considerations for vision impaired browsing here

Accommodate Older Browsers, Computers, and Dial up:
 (slow machines, dial up, ie 6 etc)

• very light weight
• minimal graphic usage (3 to be exact: logo, progress bar, and button)
• Pop up that asks users to only click on the continue button once.

Ease Anxiety / Friction Points:

• Include a phone number to call
• Include an option to request a bill be sent instead of entering credit card information.

Error Validation:

• Make it bold and proud.
• Don't make email a required field.

Side notes/Questions:

• AARP used yellow as the error validation color instead of the common red. Perhaps this was to create contrast from the logo?
• AARP error text says, "Processing Error - We were unable to process your membership request because first name is required. Please check."
  "Processing Error" sounds very technical and impersonal. I wonder if they did testing and that's what worked best?
• I am also surprised that the erred field(s) didn't get highlighted or marked in anyway. I'd imagine it's harder to identify them quickly on the form.

Source: https://mss.aarp.org/servlet/wppdispatcher?keycode=U5HAC3&packageid=&componentid=&whocalled=promo_enroll