SI units such as kilograms, meters, liters etc
They use the Metric system.
They use scientific notation for very large or very small measurements
Data is often measurements, which are expressed in numbers
If they are sensible, they will use those units defined and agreed by the International Standards Organization (ISO), as these will be universally understood and normally are required to be used in scientific publications.
They use the metric system.
Scientists use the metric or SI units of measurement.
Almost all scientists use metric units for scientific measurements.
Because
You presuppose that scientists think in the same restricted way as the rest of the population.
All scientists use the metric unit of measurements because it is the most accurate.
Measurements are facts and mathematics is the language of science by means of which the meanings of facts can be discerned.
Simply to make a series of 'standard' measurements that are recognised in any country.