For an Illustrator file, that seems perfectly normal.
Illustrator mainly draws resolution-independent vectors: images built up with curves and anchor points rather than pixels. Since
.pdf is capable of containing vectors as well, Illustrator will store its vector art in a
.pdf as actual vectors. Talking about resolution in a vector-only file is useless: it contains not a single pixel.
So, provided you haven't been using any of Illustrator's bitmap/pixel capabilities (shadows or blurs, for example) and haven't placed any bitmap images into the Illustrator file, the
.pdf file size should be identical, independent of the export resolution you choose.
Then why would a printer ask for a high-resolution
.pdf? Well, printers tend to receive bitmap-based files as well. Those do need to have a proper resoltion, for they contain pixels. I'd even guess that your vector-only job is an exception rather than the rule.
Document Raster Effect setting you mention is only to determine the resolution of any raster effect you choose to use. If you don't, the setting is moot.