At least here in Europe, they are using the same plug for charging as everyone else, so any other car can charge at a Tesla wallbox (and you can buy your wallbox by any supplier).

Once your house is wired for the charger, how hard/expensive is it really to swap it for a different one?

If you can do basic electrical wiring, you may still need to get a permit and have the change inspected. What exactly is needed is highly jurisdiction dependent.

If you are not handy, it requires hiring an electrician to make the change (~$100-500)

Spending $500 on an electrician for a $50–80k car doesn't sound like lock-in to me…

That's a decent amount of money, but it's not that much compared to the cost of an electric vehicle.