Channel 4 and ITV Apps

I really dont understand why Channel 4 and ITV are so restrictive on the devices they creat apps for - Amazon Fire Stick and Samsung Smart TVs used to have working apps. Now there seems no way to watch catch up TV for these channels unless you buy a very specific and expensive TV or if you are content to watch on a web browser or mobile device. They need to be persuaded that TV viewers should be able to watch catch up TV on their televisions either directly or through a set top boc/device. BBC IPlayer is available on my TV and three other devices connected to it so why not the others.