Why the Shaw's card readers suck

Marc Stober, a programmer, concludes that the problem with those stupid card readers at Shaw's and Star Market is not stupid programming but bad hardware:

... Theoretically you can touch "Yes" on the touchscreen - I've actually gotten this to work before they started with the tape and notes–but the touchscreens are so flighty that it hardly ever reads your response (or reads it as "No"), so the only reliable way to complete the transaction is to use the Enter button. ...

He also discusses problems with Stop & Shop's card readers.

Earlier:
The world's most annoying credit-card devices.