Because your tablets run Android and Adobe stopped ALL development of Flash for Android last year. (July 2012)
This is from Samsung Support:(07/31/2013)
Beginning August 15, 2012 we will use the configuration settings in the Google Play Store to limit continued access to Flash Player updates to only those devices that have Flash Player already installed. Devices that do not have Flash Player already installed are increasingly likely to be incompatible with Flash Player and will no longer be able to install it from the Google Play Store after August 15th, 2012.
Although not on the same timetable, I'm sure Amazon did the same with Kindle support for Flash.
There are older versions of Flash Player (for Android) at that link, but there are no guarantees any of them will work.
See also: http://forums.adobe.com/thread/1061194
I've read a lot about "Dolphin" for Android https://play.google.com/store/apps/details?id=mobi.mgeek.TunnyBrowser
I'm not an Android user (no tablet or phone) so I can't make any endorsements that would hold any credibility, but most of the Flash solutions I've read point to Dolphin as the best alternative.
Check the Android forums: http://androidforums.com/ to see what their "gurus" recommend.