That was the original definition of the meter from 1799. However, it was soon discovered that the length of the original piece of iridium was based on erroneous calculations, so it was decided that the actual piece was the new normal. Since 1960 the length hasn’t been based on actual pieces of matter but on measurements performed with light. So when you go buy a measuring tape or laser it has been calibrated by comparing it with something that is a descendant of the collection of lasers and prisms that resides in the ISO laboratory.