Fun fact: most heavy equipment just has one standard key - so most CAT bulldozers share the same key. Find them on eBay.
Some of the newer ones have electronic keypad interlocks.
People steal generators and air compressors so you’ll see those hung from a crane at the end of the day.
This is easy to defeat as you just take the crane.
Realtalk: there is a procedure to file a lien on heavy equipment left on your land (street may not qualify, check local laws). It does happen now and then that a construction company goes bankrupt or forgets about a piece somehow.