Blind in-store customers cannot be charged with actual or constructive notice of arbitration provision in retail loyalty club agreement shown on computer display at time of enrollment; the agreement, as it happens, was also illusory, as the store retained untramelled powers to modify the agreement.
http://media.ca1.uscourts.gov/pdf.opinions/16-2112P-01A.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.