Were they all the same species? There are numerous native species and while they are all superficially similar, they can display different growth habits. In general, they are all usually described as a "large shrub or small tree". Some remain distinctly shrub-like and even have a suckering habit while others tend to grow more like a tree with a single - but more usually multiple - trunk. IME, even single trunked tree-forms tend to start branching rather low and often develop into what just looks like an overgrown shrub.

No, they were not
all of the same species. 3 of the 4 A. trees were labelled Amelanchier x
grandiflora 'Autumn Brilliance', the fourth tree was labelled "Amelanchier
canadensis (Downy Serviceberry)" which may not be accurate as Downy
Serviceberry is usually Amelanchier arborea (I understand that
Amelanchier nomenclature is a mess). The 3 dozens A. shrubs were a mix of
species and cultivars of A. canadensis, A. Alnifolia and perhaps other species and cultivars (I did not
look at all labels), including about a half dozen specimens of the popular
'Autumn Brilliance' that I did see.

I should say though that
all 4 A. trees exhibit similar branching structures, with more or less
ovate crowns (and all A. bushes exhibit similar bush branching structures). However, for reasons that I explained in a parallel thread (airy
perch for birds) I wish that the tree crowns were more spreading than tall,
hence the question in the original post of this thread.

FWIW, the pic below
depicts schematically the ideal bird perch for my application, I wonder how I could approximate it
with horticultural means :-)

isnt this the same basic issue as this post?

http://forums2.gardenweb.com/discussions/4286285/small-airy-tree-for-backyard-birdwatching?n=5

and this post:

http://forums2.gardenweb.com/discussions/4279855/buying-ugly-ducklings?n=33

and wasnt the answer something along the lines.. that you buy small and prune it into the shape you want ...

or.. find a larger one.. with the work already done ....

you seem to think.. that if you pick some certain plant ... it will magically grow into the form you want .... they really dont ... someone prunes or trains it.. into a given shape ...

who that is.. depends on how much you are willing to spend ...

ken

Not quite, it is a
step-by-step search.

I started out with http://forums2.gardenweb.com/discussions/4279855/buying-ugly-ducklings?n=33
until it turned out that the beautiful tree of pic #1 is a Cornus controversa
which is not hardy in my area.

So, I was looking
for airy trees that are hardy in my area with the subsequent thread http://forums2.gardenweb.com/discussions/4286285/small-airy-tree-for-backyard-birdwatching?n=5
In that thread, I started out with photos of the Cornus alternifolia and the Crataegus
submollis to illustrate what I am after until 2 folks pointed at the
Amelanchier (great thanks!) I discovered very soon in my readings that the Amelanchier nomenclature is a mess, it is
like using the word 'red' for the color 'blue' or sometimes 'yellow'.

So, in this thread I
am focussing on the Amelanchier.

I am not an inexperienced pruner,
BTW. I have 5 conifers in my front yard, 2 of them are topiaries, 1 of them is heavily pruned and 1 of them is
lightly pruned. I also managed to kill 2 conifers that way. So I do know first hand that
you can't just prune in ways that (individual) trees don't want to be pruned
even if you follow all the rules.

Maybe you simply don't know what is possible to achieve with pruning and what is not?

I want to avoid killing or disfiguring an
expensive Amelanchier caliper tree. Perhaps I need to plant 2 or 3 Amelanchier
caliper trees side-by-side to achieve the effect in the pic in conjunction with minimal
sideways pruning. That would indeed be very expensive though, ouch.

That's one huge Amelanchier - what a spectacle!

Yeah, that seviceberry is almost certainly a champ. Ones around here are just very slender, wisps of a tree snaking upward in the forests and hardly noticeable after blooming.

Following up on what beng said, here is an Amelanchier arborea that is on my local native plant list - sheer incredulous that it has the same genes as the tree above.

There is a good houzz story on the Amelanchier [https://www.houzz.com/magazine/great-design-plant-amelanchier-signals-spring-with-airy-white-blooms-stsetivw-vs~46564099[(https://www.houzz.com/magazine/great-design-plant-amelanchier-signals-spring-with-airy-white-blooms-stsetivw-vs~46564099)