Stefan according Wikipedia;
Rabobank: ~27200 FTE.
bunq: ~100 FTE. (wiki mentions ~80, but it's a bit more by now iirc)
Small difference, the IT teams are obviously smaller than these numbers, but still Rabobank is significantly larger and can hence spend much more manpower on improving the search function. Building (proper) search engines isn't that straight forward. There is a lot of research ongoing in this field, and there is still a lot to be discovered. You can't just download a plugin for your app and have a "perfect" search options. There are sure things to be improved, but it's not that easy as some seem to think. 😀