I personally don't care who is in the next toilet. But I understand some women do, and that's fine.
Toilets are also the least of the problem IMO. I used to think it was just about toilets and transphobia, and I absolutely think trans people should be allowed to live their lives free from discrimination or harm.
But that shouldn't come at the expense of sex segregated spaces and services which are segregated for a reason.
Summing it up as just toilets is misleading. How would you feel about:
-Sharing a prison cell
-Sharing an open changing room, including showers
-Sharing a women's refuge, after suffering rape or abuse
-If you run a service for women from your home, Male bodied women should also be able to gain access to your home for this service - you are not allowed to refuse.
-School changing rooms segregated by gender instead of sex
-School and child's group activity accommodation segregated by gender (eg teenagers with penises and vaginas sharing accommodation, rooms and tents on school trips) without parents knowledge
-Competing in a sport against someone who had previously been in a different category due to innate biological differences
-Competing in a contact sport with someone who is taller, heavier and stronger when this would previously have been disallowed, risking injury
-Medicating and stopping puberty in children and teens who are still figuring out who they are as a person
And if you would be ok with it, do you believe women should have the right to object to have a Male-bodied person in a space where they are vulnerable, or should they just put up and shut up?
Women have the right to feel uncomfortable in these situations. And, whilst the majority of trans people want to live their lives in peace and don't pose a risk, there are some people (genuinely trans or not) who are abusing the situation. There have been real "casualties" of self ID:
-Multiple Male bodied sex offenders are in female prisons. Several women have been raped or sexually assaulted as a result, including both prisoners and staff
-Official guidelines for some women's refuges and rape centres state that if a victim is uncomfortable with being in proximity with a Male bodied person due to their trauma, they should be refused help and sent elsewhere
-Multiple women have suffered severe injury as a result of playing contact sports with a Male-bodied person
-Several women in Canada have been sued, lost their livelihoods and reputations because they run a women's genital waxing business from their home, and would not agree to wax a trans woman's penis in their home (which aside from comfort or risk concerns, is a different procedure which requires different equipment and training)
-As well as your garden variety perverts taking selfies in women's changing rooms with naked women behind them, asking online if "as a woman" they should help young girls put tampons in if they see a child in the girls toilets, walking past a primary school with their penis hanging out of their skirt, etc
- A 9 year old dancing for adults at night in a bar for cash tips (including some cash put in their underwear) is celebrated because they're a drag queen and therefore brave for breaking down boundaries
-Children are more pigeonholed than ever before. Rather than letting a child discover their identity in their own time, on their own terms, children displaying behaviour outside the gender norm are more likely to be pushed down a pathway which can end in medication and surgery
-Young teens and adults who are now transitioning, who far from having the support of the trans community are shunned and silenced. They've gone through irreversible medical procedures and are now infertile, and still don't identify with the body they inhabit
-A push for demedicalisation of gender dysphoria, meaning that counselling and mental health provision is woefully lacking
(I can provide citations for all of the above if needed, but CBA without request).