Mrs can be pronounced easily by all - unlike Ms - which can sound dreadful.
Only because we've learnt it. While English orthography is quite often confusing, it does have rules and usually expects to have at least one vowel. If you're not a native English speaker, how do you know it's not pronounced "emmarress" or "muuhrs" or something? It's not harder learning how to say Ms as "muhzz" or "mihzz", and there are plenty of English accents, so you're bound to get a bit of variation, anyway.
When I was at school in the early '80s, we had a new teacher who was Ms Brown (well, she actually had a different surname, but she was definitely Ms.) There was quite a lot of speculation among our parents about whether she was divorced, because she was Ms - I was about the age where I was only learning there was any such thing as divorce in the first place. I have no idea to this day whether she was divorced or not. And all of us learnt quite quickly that she was Ms, and not Miss or Mrs, because she was quick to correct anyone who didn't get it right. I imagine she's still doing it to this day (unless she's retired), as there are some people to whom every female teacher is Miss, whatever they've been told.
It's not trivial, though - of course they shouldn't, but people do judge you on whether you're Miss, Mrs or Ms - this thread (and many previous similar ones) are proof of that. People will be making assumptions about you being married, or divorced or not being able to find a husband, or being a mad feminist lesbian. Most of the assumptions are going to be wrong, and almost always irrelevant, but they still happen. Yet if you have correspondence from Mr Smith, all you're going to know is that he's a man. You're not going to be able to make assumptions about whether he's married, single, divorced, straight, gay or anything else, because men just don't have that history of the title Mr having particular associations, because there's not the same history of men's social status being dependent on someone else (another man) in the way that women's have been. When I was clearing my parents' house, I came across a tax return form for about 1973 in my father's desk - it included a section for dependent adult daughters. That's round about the same time that the last marriage bars were abolished (in the civil service) for working women. Such freedoms were hard won and could be depressingly easily lost. Workers' rights have been diminished quite a bit in recent years.
(My mother, who was sometimes a bit archaic in some ways, would address letters to friends as J. Smith, esq, and only use Mr J Smith on business correspondence, because the Mr indicated tradesmen. She was born in the 1940s, not the 1840s... But I'm trying to point out that there did used to be some distinctions in male titles.)