UKF has 30 different units. OKW has 28, Ostheer has 31 and Soviets and USF have 33.
Almost all of which are locked into single doctrines. Many of which would clean a lot of the problems with Brits if they were added to the mainline roster.
UKF has 10 standard stock units (11 with medic squad) + 2 side tech ones + 2 emplacements (mortar pit and 17 pdr)
Most commanders give you 1-2 doctrinal units as well
Soviets have 11 units in T2 builds, 14 with T1.
USF with one officer tech has 9 units (plus ambulance and the officer) or 12 if everything is teched (+2 officers)
OKW has 11/14 depending if you want to have full tech (+1 for the KT on full tech)
Only Ostheer has a lot more with 15 if you go for full tech.
Not sure what your point is. If it comes down to builds, I agree that UKF is a bit bland because of they are missing the indirect and a second LV, so their tech is quite predictable (especially in the current meta). On the other hand all faction except for Ostheer usually go 3-4 mainlines +2-3 support weapons on the infantry part.
Its more than that. The faction has a bunch of stuff that just doesn't perform the way it should or is incredibly awkward to use in its intended role. Especially at T2, where the entire tier is a mess.
Royal Engineers coming out in T2 means that a large chunk of their role was either automated (self repair) or else moved onto sections. (Trenches, Caches) The unit needs to either lean harder into its short range role or else its utility role.
The Assault Officer has an awkward combination of abilities, and being able to purchase only a single one limits what kind of playstyles you can use with him. Like the Engineers, I think he should lean more into the CQC role, more into the officer role, or else be redesigned so you can call in multiples. Funnily enough it also would probably be the best user of the Arty calldowns, yet doesn't have access to them.
IS also don't really get weapon upgrades for their line units in the midgame. This works for Soviets, (arguably) but its forced some awkward abilities (cover bonus, 5 man) on IS to keep them relevant with other factions. A lot of this could be rectified to rethinking the IS upgrades, but any push toward that gets stonewalled. Weapons like the Vickers have little role in the game, but could be easily redesigned to give IS some attacking power for example.
Even the Snipers AT role is incredibly awkward to use, and he's often too valuable to risk using in that manner for what is often a fairly 'meh' set of crits.
The tech upgrades (AEC/Bofors) are likewise uninteresting. They should have worked like Hammer/Anvil (unlocking multiple units and upgrades) but not locked each other out of being purchased. This would work as a mini tier where you would have the choice to invest in 0, 1, or 2 before going up to T3, with tradeoffs to each choice.
And this is all before we even get into its lack of choices in light vehicle play.