@nealg – I think what you are not currently understanding is that the filters that are going to be implemented are not yet in place.
Google has it Safe Search thing but at ISP level it is up to people to set their routers etc accordingly. If you contact your ISP and ask them about parental controls etc they will guide you through setting your router and software local to your computer.
Further, ISP’s can block specific sites (think Piratebay for example) and specific IP addresses or blocks of IP addresses.
What the government is forcing upon the ISP’s is the obligation to provide internet filtering at point of source in effect and mandating what is and isn’t ‘allowed’.
This is a step change and in my opinion a dangerous one. it is not the filtering on goat porn or whatever that bothers me. It is the fact that a framework is being established that would allow a government to instruct an ISP to filter certain content and for that filter to be implemented.
We are being given a choice at this stage whether or not to accept the filter but there is no guarantee that this choice will always be offered.
This isn’t tin foil hat stuff and the current and / or future governments may never take it that far but it makes it all the more possible and all the easier for them should they wish to.