Hardware requirements vary widely between providers, depending greatly on whether or not customers manage their own broadband circuits. Each circuit terminates on a device (a modem, in the case of ADSL, ADSL 2+ and FTTC) which requires cabinet space, power and cooling.
Each modem is plugged into a bonder, acting as the default gateway for the router/firewall to access the internet. Some providers, instead of using a single, dedicated bonding device, prefer a master/slave arrangement using integrated modem/router devices. These are usually consumer-grade devices with adapted firmware. This configuration lacks a single ethernet port to connect, so requires an additional switch, which of course also needs space, power and cooling.
Some providers also place limits on the throughput handled by individual devices, requiring, even on a mediocre connection, further additional hardware units, each line using a modem, router and switch. For a 4x Bonded ADSL connection this would mean nine devices, all requiring space, power, cooling and interconnecting cables, before the firewall.