A total of 66 taxi drivers were issued official warnings last year after their taxi-meters were found to be inaccurate.
However, the National Standards Authority of Ireland says only one required further investigation after a follow-up inspection.
"Last year, we inspected over 3,200 supermarket scales - those are the ones you find at the till - and 202 failed," said NSAI chief executive Geraldine Larkin.
"We issued warnings and when we went back again, only four required further investigation.
"Similarly for fuel pumps, we inspected 7,693 fuel pumps, and 289 failed. That was reduced down to 15, once we carried out our follow-up."
"Most of the time, we find that those that fail our inspections do so due to normal wear and tear.
"But regardless, the instrument is immediately taken out of service.
"But if we suspect that an instrument may have been tampered with purposefully, we can prosecute the trader in question – and we ask people to be vigilant and report any suspicious activity to us directly."