Here in Finland mechanical locks with electronic keying are pretty common in some places. Some of them like iLOQ or Abloy eCLIQ are actually pretty clever: electrical bits of the lock are powered from mechanical action of inserting and turning the key, so you don't have to worry about batteries. In theory, they promise significant cost savings in scenarios like rental apartment buildings where tenants move in and out, need access to common areas, lose keys, etc, without compromising security or having to replace or recode locks - they just give you a generic key, click some buttons in the admin panel, and your key could be provisioned accordingly once you first enter the building and interact with one of the "smarter" locks that are externally powered and networked to the mothership.

In practice, in addition to the usual bugs you would expect from a software-based system managed and maintained by a plethora of organizations and contractors, they tend to become very annoying as parts wear out, so you have to fiddle with the key reinserting it repeatedly trying to find just the right angle so it will make a good contact to be recognized by the lock (for example the iLOQ system by my landlord communicates over a thin contact strip molded into the key opposite of the cutting and separated from the rest of the key with a thin layer of plastic).