The "proof" part of proof of coverage is very weak in Helium currently. Clearly most people are in good faith, but it is inherently vulnerable to Sybil attacks,

The "proof" part of proof of coverage is very weak in Helium currently. Clearly most people are in good faith, but it is inherently vulnerable to Sybil attacks, because there's a chicken and egg problem with starting a new group of hotspots in an area with no external 'trusted' hotspots to validate them.