Does LZ4 compression have an effect on JSONB columns?

After doing some experimentation, it appears as though COMPRESSION lz4 doesn't have any effect on JSONB columns (whereas it does for JSON, and TEXT). Is that indeed the case? If so, why is that? I could dive into the Postgresql mailing lists and/or source code to try and find the answer, but hoping someone who already knows the answer can chime in.