ATM cards spread relatively quickly. Since the cards were used in public, others who did not yet hold the cards could see how convenient they were. Although some people were concerned about security, the convenience factors seemed to be a decisive factor in the “tug-of-war” for and against adoption.
The case of credit cards was a bit more complicated and involved a “chicken-and-egg” paradox. Accepting credit cards was not a particularly attractive option for retailers until they were carried by a large enough number of consumers. Consumers, in contrast, were not particularly interested in cards that were not accepted by a large number of retailers. Thus, it was necessary to “jump start” the process, signing up large corporate accounts, under favorable terms, early in the cycle, after which the cards became worthwhile for retailers to accept.