With those $300 dollars difference a landlord would need to cover insurance, property taxes,

These are included in mortgage payments. They go into an escrow account and are paid by the mortgage lender.

regular maintenance like replacing roof every 30 years, unplanned maintenance like a pipe bursts or aircon breaks. On top of that someone needs to act as the property manager/handyman so either the landlord takes that phone call on a Friday evening for the pipe that is gushing, or is paying someone to do that.

Yes, that is part of owning property. Rent shouldn't necessarily cover the mortgage plus all costs associated with owning the property. The property owner might be taking a loss during the period when they have a mortgage, but they have a property that's probably worth hundreds of thousands of dollars or more, so they're coming out considerably ahead. When you get people who feel they're entitled to have all costs + the mortgage covered + be able to live on the profits in addition, that's when you get shitty serial landlords who don't ever meet or talk to their tenants.