The .30-06 is inexpensive to shoot in USA... especially if you are not a handloader. Practice rounds go for $6 a box and military surplus rounds are commonly available. The .30-06 is available everywhere so it is handy for out-of-state trips when you need an emergency supply and it comes in a wide variety of loads although the 150-grain is the most common. I noticed the popularity of the .303 in RSA so I imagine there are similar advantages for that round there. Whenever I go on an out-of-state hunt, no matter what rifle I am using I usually throw in an old .30-06 as a backup rifle for the above reasons. I've never needed it but others have borrowed my rifle when their's crapped out. Actually though the most common field failure has been scopes rather than rifle. My old 06 backup is an open sight Mauser rifle and quite reliable. It is not glamorous but it gets the job done. I imagine the same can be said of the .303.