It depends on the kind of meter that your utility uses and how they have it configured.

Smart meters can measure that data at higher frequencies (up to several kilohertz) and from that data you can detect signatures that identify devices inside your house and even, in some cases, what they’re doing. For example, when your washer turns on it runs a pump (which draws a specific load) for a set amount of time and then goes through a cycle of running a motor to agitate the load, which draws energy in a specific way as it turns back and forth. When you turn on an LED light, it runs at a steady rate and draws the same amount of energy. When your AC runs it draws a different amount of current than the washer or LED.

With enough data, over time, you can determine which devices are in the house and when compared to a database of known signatures you can classify the device. Ex: all Samsung Refrigerator Model 23e4234 work the same way so once you identify the signature of one you can identify others.

Here’s some articles talking about it:

https://www.sciencedirect.com/science/article/abs/pii/S2352467719300748

https://energyinformatics.springeropen.com/articles/10.1186/s42162-019-0096-9

Also, just because your meter is only normally reporting every few seconds it doesn’t mean that it isn’t capable of recording the data faster for diagnostic purposes (“Why is this house suddenly using 10x the power?!”) or law enforcement purposes (“What house in this neighborhood is using HID lighting?”).

Not all meters have this capability. Old style meters with a disk don’t record data at all and some of the older smart meters can only sample at lower frequency. You can do the same math on the lower frequency data but if you can’t measure fast transient events you lose some of the more specific capabilities (like knowing the exact model number of your refrigerator).