This is what is stored in your SVG file concerning the rectangle’s size:
Not 17 x 20 m or 17,000 x 20,000 mm, but all in SVG’s own arbitrary unit system, which to my knowledge is based on pixels (with 1 mm = 3.543307px).
Let’s do the math:
width = 60236.219 / 3.543307 = 17,000 mm (so far, so good),
height = 70866.141 / 3.543307 = 20,000.00028222223 mm (oops).
So, not even with SVG’s internal unit system you will get a mathematically “clean” result for the height. Now add the aforementioned imprecisions in floating point conversions on top of that and suddenly a deviation of 4 mm over a length of 20 m sounds not so bad.
Care to elaborate how this is a “problem” for your workflow?
Frankly, this example seems a bit contrived to me. Blender is not supposed to be a tool for any kind of high-precision modeling anyway. And for visualization purposes - well, who is ever going to spot a deviation so tiny?