alt Hacker NewsThey are complicated, but standardised and commoditised. Ubiquiti, for example, sells an ONT (fibre modem) in a SFP form factor for US$39 [1], or a little standalone unit with an Ethernet port for US$49 [2].
1. https://store.ui.com/us/en/category/fiber-gpon/products/uf-i...
2. https://store.ui.com/us/en/category/fiber-gpon/products/wave...
For comparison: you can bring your own DOCSIS modem to a cable network, even though all the houses on the street are connected to the same cable and you could jam it, or send a voltage spike to break everyone's modem.