Although I prefer pole snap beans, I too would have to agree that bush beans 'turning to mush' is an over generalization. There are good bush varieties for canning & freezing, just as there are bad pole varieties.
I also got a kick out of the whole 'using a ladder to pick them' thing. There's a simpler, far less dangerous alternative... which is to use a shorter trellis.
Personally, I've found that the "filet" type beans are some of the best freezers. They are firm, slow to develop seed & string, and freeze well. "Fortex" is a pole filet type, as is "Emerite", which IMO is the gold standard for freezing. "Nickel" and "Maxibel" are two bush filet beans.
One of my favorites for flavor, though, is still "KY Wonder". It has a softer cooked texture than the filet beans, but the rich flavor is hard to beat. Some of the thicker Romano types are fairly good frozen also. These softer beans need more attention both during the freezing process, and in the way they are prepared after freezing. It took me a lot of years, and a lot of mushy beans, to figure that out.
Which brings me to one more comment re: beans turning to mush. Choosing the best variety & freezing properly are only part of the picture. How you cook snap beans
after freezing also has a lot of influence over the final texture. Frozen beans need very little cooking, and are easily over cooked... which makes them mushy. I recommend not pre-thawing prior to cooking, and sampling once a minute after the first 5 minutes. Pull the beans out of the water just before they reach the desired texture, since they will continue to cook a little more until they cool. The use of a strainer basket makes quick removal easier. I stir cold margarine into the beans immediately, which has the advantage of helping them to cool more quickly... but you can also place the basket briefly under cold running water (or a sprayer) until the beans are just warm, to halt the cooking process.