When there is no vehicle load on the trolley wire, the ammeter and thus the watt-hour meter read near zero. Been there, watching meters. A voltage detector at the far end would consume pocket change per month. Admittedly, rotary converters at no-load do consume a wee bit of power. Solid state converters - almost nothing. But a lot cheaper than copper.

If any property custodians have or will take action, almost nobody will know until the police arrive. At least, that should be the intent.

Thanks for your interest.