A scientist adds uncorrupted beakers to a town, which are then multiplied by whatever buildings are present (lib, copernicus'). A tax collector adds uncorrrupted tax income to a town, which is then multiplied
Specialist-generated income/beakers are not multiplied by buildings! Only commerce converted through the sliders goes through the multiplier-buildings.
This is why, once a (core) town has a Lib + Uni (which together double the town's commerce --> beaker output) it's preferable to have all commerce-generating workable tiles being worked by citizens (if possible), rather than running those citizens as Specialists.
It's also why Banks are useless when running Sci%+Lux%=100% (i.e. Tax%=0%), because the Bank's "+50%Tax"-multiplier effect has nothing to work with.
And it's why it's not worth putting purely commerce-multiplier buildings in 'one-shield towns' --
that's where growing massive excess food to support Specialists is preferable.
I recommend searching out the articles "The role of the Specialist Citizen" and "Multiplier buildings a practical primer" in the War Academy.
Thanks, all. Is there any way to tell how many beakers a given tech costs?
You can see the 'base cost' by looking in the .biq file using the Editor, but this is adjusted (multiplied) for any given game based on chosen map size and difficulty level. Total cost to learn (or buy) an unknown tech is also re-adjusted (downwards) based on how many civs you know which already have it.
In-game, provided that you can generate enough beakers to learn a new tech in less than 50 turns, you can make an
estimate of the (current) total cost of a tech by playing with the Science-slider in the F1 screen, while watching how that affects the numbers "science per turn" and "turns to learn tech".