Here are some things that will happen if sex is NOT a mandatory category on the census
Within only a few years, we will stop knowing what the rate of sex-selective abortion of female fetuses is, or in what regions those rates are highest.
Within a few years, places that usually show a skewed sex ratio of adults due to highly gendered workplaces (for example, cities with oilfields and many temporary male workers, or capital cities with many women in low-level government jobs) will not be able to plan or budget according to known factors—for example, planning for female or male-specific healthcare, or prisons.
Within 10 or so years, we will lack any verifiable data on the oppression of women and girls. We will not know if they are underrepresented or overrepresented in certain jobs, we will not know what the wage gap is (or if it exists), and we will not be able to make data-based arguments for programs that support women and girls.
Within 20+ years, we will no longer even have verified proof that the sex ratio of human beings, is, on average, roughly 52:50 females to males, with male infants slightly outpopulating female infants, and female elderly people being much more populous than male elderly people.
This means that MRAs will finally achieve their dream—being able to make the spurious argument that, for example, women are not underrepresented in the highest levels of corporate and governmental power. Maybe women really are just 10% of the overall population, so it makes sense that they are 10% of XYZ’s board of directors, or cabinet ministers. Maybe women are actually dramatically, rather than slightly, overrepresented in certain fields (like law school), so we need to do affirmative action for males.
Prison planning will now be very difficult for all cities, not just the ones with highly dynamic sex ratios and temporary workforces. Likely, planners will just save money by building very few female prisons, and overcrowding them if necessary. This is assuming that male and female prisons are still segregated at all, though. If, in the MOGAI hell world, we decide to do mixed-sex prisons, female prisoners will likely commit suicide before or after being subjected to multiple sexual assaults a day, and constant harassment.
Data on male violence against women will become nonexistent. We will only have statistics about human violence against humans, which makes it difficult to know which humans need a special shelter with a secret address and a detailed plan to escape another human.
Obviously, the problems with health care planning will be tremendous. Even assuming that individuals still have proof of their sex, but that sex is not recorded on mandatory census forms, accuracy in allocating funds to sex-specific healthcare needs will be drastically reduced by lack of accurate data.
Census companies will take advantage of the growing corporate demand for census data. However, their data will be fractured, market-based, and targeted only at specific consumer populations. (For example, what percentage of people in income bracket $25-50,000 and neighbourhood LMN are male and female?) Some companies will deliberately engage in biased data-collection processes in order to skew data in the way their commissioning company wants.
Companies competing for government contracts will use skewed and dishonest private data sets to make it look like their particular services are absolutely necessary and urgent.
One thing will not change in this new world, however. Pimps and porn directors will still know who exactly their clients are, and what sex of performers they want to see. Prostitutes will still know where the men live. Strippers will know who yells verbal abuse at them, and tries to touch them. Johns will know that biologically female women are the people they want to abuse.