Answer
All the infrastructure is based on English system that needs to be redesigned.
Work Step by Step
English system includes units of measure like gallon, inches, feet, yards, pint, miles, etc. These units are used since very long ago and used very generally in the United States. If these are eliminated instantly and the metric system is applied, then this would create a lot of confusion in the people because they are not used to the metric system.
In the beginning, the units of English system were not uniform all across and that’s why there arose a need for metric system. Metric system is uniform all over the world and they are very easier to use. They are in multiples of ten and easy in the comparatives.
Hence, overall English system has no advantage over the metric system; however, people are used to it and might need some time to change.