When I worked on a TPMS system around 2007, we couldn't get the VIN off a sensor. We could get the sensor id and maybe the tire id (depending on the type of TPMS system). We had access to the VIN in our flash, as well as access to it over the CAN bus from a number of sources. I'd expect that you would have a very difficult time measuring random vehicles sensor ids and readings if they're just driving by because of how low throughput the system was.

Signal isn't really that strong, a few feet away and your not gonna be able to capture that data.

Yes and no.

Direct TPMS sensors that use RFID transmit a serial number but probably not the VIN.

Many cars use indirect TPMS which uses the ABS sensors to measure rotational difference between wheels, thus indicating a low-pressure situation. No RFID is used.