1. Everything uses a common base, so you don't get a base change on a scale change (or indeed, two different bases for different parts of the same measurement), and dimensional consistency becomes trivial.
2. The base is base-10, which is the same as our common counting system.
There are two exceptions I’m aware of to “SI is easier in practice”.
1. Temperature. It’s useful to elongate units over the range normally experienced by humans, which Fahrenheit does and Celsius does not, because it avoids tenths of a degree, for example, in room temperature selection.
2. Woodworking and similar: it’s useful to use powers of two because it’s very common to be marking/cutting/etc. 1/2 or 2x a value, which is easier to do in inverse power of two English measurements.
I've found metric to be better for woodworking, and especially metalworking. Powers of two (imperial) are no easier than doubling a metric measurement, and more difficult when partitioning items items in thirds or fourths, or having to cut wood in half with lengths like 56 and 7/32 inches (1428mm).
1. Everything uses a common base, so you don't get a base change on a scale change (or indeed, two different bases for different parts of the same measurement), and dimensional consistency becomes trivial.
2. The base is base-10, which is the same as our common counting system.