I know that certain matches in the UK aren’t restricted to be broadcast in certain regions like the NFL or Baseball games. Are all matches post 3PM broadcast?
There are usually 10 Premier League games each weekend with 3pm on Saturday the traditional kick-off time. The blackout from 1445-1715 exists not only to protect attendances at the Premier League but also all the way down the lower leagues, where matches also mostly kick off at that time. So televised matches have always been shown outside of that window, firstly on Sunday afternoons and Monday nights but as more and more games have been included in each new TV rights deal, more Sunday slots have been added, Saturday early evenings and lunchtimes and most recently (and not entirely successfully) Friday nights.
There's some talk now over what remaining slots can be used and one suggestion is that there may be some simultaneous kick-offs, for example two rights holders having matches in the same slot. This has never been done before outside of the final day of the season, where all 10 games are played at the same time and Sky shows 2 or 3 where something is at stake.
Internationally, every single game is sold in the package and there are many countries where they are all made available, and there would be a great demand if this would be made available in the UK but this won't happen while games are played during the 3pm blackout. The opposition to moving more matches outside of Saturday 3pm is not just due to tradition but also because of the way it inconveniences fans who attend games - as a season ticket holder I always have to wait for each month's televised fixtures to be announced before I know whether I can make it to games and for away fans (many more travel to away/road games than in US sports) it means waiting to confirm travel plans and evening games can be problematic for fans travelling long distances.
Another idea that sometimes comes up is clubs selling their own rights and fans subscribing to just their team's games. This won't happen while all 20 teams have a vote as at present 50% of domestic rights money is split evenly between all teams, with 25% based on league placing and 25% on number of TV appearances (with rules in place to ensure minimum and maximum appearances for each team). Clubs selling their own rights would increase the financial gap between the bigger and smaller teams. There was recently an attempt to change the overseas TV rights money, 100% evenly split between clubs, to give more to the bigger teams who attract the big audiences worldwide but this was shot down by the rest of the league.
The nearest thing we have to the Red Zone is BT Sport's Champions League Goals Show, which moves between all eight simultaneous Champions League group games, with quick replays of all goals and major incidents. It can be done because the rights all belong to one broadcaster and they can (well, contractually must!) show all matches in the competition. It works really well and is a great watch when there isn't one particular game you want to see. I hope it'll still be possible to do from next season when there'll only be six matches at 8pm with two moving to 6pm.