The gemara makes a statement that we are not able to learn out issues that effect issur and heter, from monetary issues. This implies that the burden of proof necessary for issur must be stronger and more convincing than the burden of proof necessary for monetary issues. Tosafos asks that the exact opposite seems to be true, because we follow the majority for issur issues (even against a chazaka), yet for monetary issues we say that we don't follow rov. Do we require the proof to be stronger for monetary issues or for issur issues?
Tosafos answers that generally we assume that the proof necessary for monetary issues is greater than for issur. It is only in this specific type of issur such as marriage/divorce do we make an argument that the proof must be more substantial than by monetary issues. The precedent for this is from "mayim sh'ein la'hem sof" where we don't follow rov, rather insist on absolute evidence. Now, the concept of "mayim sh'ein la'hem sof" is only a rabbinic chumra. Therefore, on a d'oraysa level we would be able to learn all issur (including marriage issues) from monetary issues, but m'drabonon we are extra strict when it comes to marriage and divorce.
The maharatz chiyus has an exact opposite approach from Tosafos. He asks from the gemara later 27b that assumes that if the concept of returning a lost object to the owner through simanim is d'oraysa, we can also return a gett with simanim. Why don't we say that we can't learn out issur issues from monetary issues? The maharatz chiyus explains that specifically for marriage and divorce type issues which are totally under rabbinic control, do we learn issur from money because monetary issues are also entirely in the hand of beis din.