The only company with a "proprietary" charge port is Tesla. Everyone else uses J1772,CCS or CHAdeMO connectors (and I can't recall off the top of my head the interoperability between J1772/CCS/CHAdeMo). Tesla does sell adapters so a Tesla can charge at a non-Tesla charger, and I think there are adapters so non-Teslas can charge on Tesla's networks.
Many EVs do come with an on-board charger that can accept "home" power - but it's terribly slow; in the US most circuits are only 15 amps, which at 120V means a whopping 1.5kW charging rate - good for emergencies but not much else. I bought a Level 2 charger to install in my house - it's wired to 240V with a 60A breaker; it's rated for 11.5kW charging - basically overnight.
But the charging networks - there are quite a few competing networks, and I think they are using their revenue to build out capital, rather than provide cheap service. Given that residential power is available in many states around $0.12-$0.18/kW-hr, networks charging $0.30 or $0.40 seems... pretty high to be honest, given those networks can probably get power at "wholesale" prices. Granted fast-DC chargers are 200-350kW, which is pretty fast when the batteries can handle it (battery charging is quite nonlinear- they can pull massive power when "in the middle" but the closer they are to 100% charge, the slower they can accept energy; the last 10% of charge can take I think as long as the previous 50% or something like that.
I don't expect point-of-sale prices to ever drop, even for those networks that "make their own power", because why would they? They just have to compete with gasoline, and aside from refueling time, they do that currently.
As a consumer, I'd definitely like prices to be lower...I wonder if the nature of electricity can allow for more differentiation between networks, giving some the ability to charge less than others. After all, electrons are even more fungible than gasoline and don't require refineries or anything.