For many European banks the math is even more brutal.

In some jurisdictions if bank can prove that transaction was made with customer's key then customer can not demand their money back. That's the best case, but there are only few of such jurisdictions and even there the burden of proof is on the bank and it costs a lot.

In other jurisdictions bank must reverse a transaction even if it was proven that the transaction was signed with a legitimate key, but the key _may_ have been stolen.

In some jurisdictions (i.e U.S.) banks are required to reverse a transaction at a customer’s request, even if the customer does not dispute having made the transaction.

In any case dealing with all this is too expensive and risky.

If someone steals the secrets from a rooted phone and steals customer's money the bank is on the hook, so banks do everything they can to minimize this risk.

There is no way to store customer's secrets in a PC browser securely, so all the "dangerous" transactions were outright prohibited in the web app or made available only via temporary QR login.

All this is just is a negative side effect of customer protection laws.

Unlike gas furnaces which basically can only do ON or OFF, heat pumps can regulate the heat with much higher granularity.

What certainly calls for innovation is managing the labor costs. In my case installation involved way too many people and way too many visits.