There are two related issues. Stopping the use of standard units will cause total chaos. You cannot have trade if the two parties do not know what quantities they are dealing with. And without trade most countries' ecomonies would collapse. Also, you would have distasters like the Mars Climate Orbitter - a lump of scrap metal that NASA sent, at enormous expense, to Mars - useless because they mixed up SI and non-SI units.
Second, one of the main advantage of the SI system, and the reason that it has caught on across the civilised world, is that moving from larger to smaller units (and conversely) is all done using factors and multiples of 10. Since we count in the base of ten, these conversions are relatively simple. Just knowing a few prefices is enough whether you are working with mass (weight), length, volume, time, electric charge or whatever. The Imperial system was an absolute jungle of multiples of 2, 3, 4, 6, 8, 12, 14, 16 and so on. This requires familiarity with so many multiplicatin tables.
You may not have any units. Standard units are not used in data on household size, for example.
kg
There are several, collectively known as the SI units.
International System of Units (SI)
SI is short (in French) for International System; the international system of units, used all over the World.
we cannot get a correct measurements
The principal SI units used to derive all other SI units are the base SI units. These are the units for physical quantities such as length, time, mass, electric current, temperature, amount of substance, and luminous intensity.
they are units for scientist
People would understand better and the world would be more ordered; and SI is an absolute necessity and obligation for all the rational and intelligent peoples.
Nothing real - all measuring units are equally valid - BUT there would be a bit of human confusion.
When SI units combine, they create derived SI units that are used to express physical quantities. These derived units are formed by multiplying or dividing the base SI units. Examples include the Newton (kg*m/s^2) for force and the Pascal (N/m^2) for pressure.
Watts
the Meter
There are different units for measuring different attributes.
You may not have any units. Standard units are not used in data on household size, for example.
SI units, which is the abbreviation for International System of Units, is used for making measurements that can be understood in various countries. While most countries have no adopted SI units as their form of measurements, some countries like the United States only use them in certain areas of study.
The SI units that can be used to describe the mass of smaller objects are grams (g) and milligrams (mg). These units are commonly used for measuring the mass of objects that are relatively light or small.