I emigrated to the US as a fiancée. It was not necessarily easy or cheap (I'm agreeing with you) and I came from a "low visa fraud risk country" (Australia). Some of the challenges faced:
It probably cost around $30,000 all up. Every visit to a consular office or USCIS cost about $100 in biometrics alone (each time). Fees for applying, fees for adjustments.
My partner and I had an issue where I was supporting her (she was in school). The system is not set up for that, and expects the US citizen to be financially supporting their prospective spouse. I realize that there are challenges around our situation in terms of providing a financial benefit to a USC that could be construed as paying for a visa.
I was interviewing for jobs in the US from Australia as my move date got closer (after the visa was approved). Siemens nearly torpedoed things when they wanted to start a H-1B or other visa app for me even after being repeatedly told I didn't need one.
My fiancees family ended up having to sponsor me, signing declarations of financial responsibility, that they could be made to repay any government benefit I claimed within the first 10 years of living here (tied to that previous issue).
Some of the evidentiary requirements (bona fide relationship) were reasonable and actually quite clever (separated, and asked questions like who usually does dishes, or takes out trash, and what day is trash day for that matter, and beyond) and others were onerous (I had to pay BoA an exorbitant amount to get all bank statements for 3 years, copied and notarized).
In the end, ironically we determined I would have been "adjusted" to a unconditional LPR more quickly, and more cheaply, if I had come here on a visa waiver, promising not to get married, and just got married and said "oops, my bad, can I be converted anyway?" than actually doing it the right way.