FrankR
You are correct about small tractors being used for 'truck' type farming (vegetables). Many of the major tractor builders did build what looked one step up from 'toy' tractors for this market. One really odd looking light tractor was built by Allis Chalmers, and resembled a 'go kart' with a small 4 cylinder engine mounted behind the operator's seat, and cultivator tines hung midships. John Deere built a very small 2 cylinder tractor, but the most popular of these small tractors was, IMO, the Farmall Cub. These turn up all over the place, and must have been in production for decades. These were used on small vegetable farms as well as for mowing large lawns and miscellaneous work around rural properties.
Another 'assembled' tractor which was capable of a lot of work was the "Economy". This beast had a one cylinder air cooled engine ( Briggs and Stratton, usually), and was assembled from automotive parts. Some had hydraulic pumps and could run a small loader. Most had belly-mounted mower decks and some had snow blades. Many were used for light farming on vegetable gardens. Now, the "Economy' tractors are quite collectable.
An overlooked specie of 'real working tractor' is the original 2-wheel Gravely tractors like the Model L. These were a solid little workhorse, having a cast iron transaxle and massive all geared drive. Gravely made their own engines, a "T head" configuration with an assembled crankshaft (the original inspiration for the first Gravely being an Indian single cylinder motorcycle engine). These little tractors featured full pressure lubrication, and a wide variety of implements was available- there were mower decks, sickle bar mowers, reel/gang mowers, snow blowers (including the infamous 'Dog Eater'), orchard sprayers, buzz saws, a PTO shaft to allow the tractor to drive other equipment, cultivators, rotary soil plows, and much more. The Gravely tractors saw use in a wide range of applications, which extended even into cities where they were used for clearing snow from sidewalks and schoolyards. Small farmers used the Gravely tractors for getting vegetable plots ready for planting and for cultivating. These were serious little beasts and could be ordered with a belt-driven governor (Pierce governor, I think). There was nothing lightweight or 'homeowner grade' about anything the old series of Gravely tractors had. The Gravely tractors were built in Dunbar, West Virginia until maybe into the 1970's. Somewhere in there, the cost of building the Gravely engines in-house got too expensive, and the low horsepower rating ( 7.6 HP at maybe 2000 rpm) forced Gravely to go over to Kohler engines. The Gravely tractors fell out of favor due to the fact you need some muscle to run them, and you need a wrench to change implements. Modern suburbanites are not going to put up with a multi-purpose 2 wheel tractor where you have to undo four bolts and have some muscle to swap implements. The Gravely tractors have given rise to a cult following. I bought a Gravely 7.6 HP 'Super convertable' (2 speed axle option) in 1983 when we bought our first house. I am still using it occasionally, having picked up a Gravely Commercial 10A with the Kohler engine and 34" snow blower attachment. My wife has a little fun when she either sees someone riding on an old BMW "Airhead" motorcycle, or, hears them discussing having a lathe in their home shop. My wife will ask these people if they own a Gravely as she is convinced that there is some genetic link that causes people who either have a lathe or ride an Airhead motorcycle to have at least one Gravely. Surprisingly, this is not too far off the mark.
I see the 'light power equipment' sold to homeowners and property as 'commercial grade' or similar. While it certainly does the job and does it a lot easier than horsing a Gravely with a mower deck around, or trying to maneuver a Farmall Cub with belly mounted mower, the new equipment just does not seem so rugged or as if it is going to last as long as the older tractors and implements. My other tractor is a 1979 Yanmar 195D, a little 2 cylinder compact diesel tractor. All geared driveline, front axle drive, and the engine is amazing. It is an iron block diesel with sleeve liners. Successive generations of compact diesel tractors have gone to 'ladder block' design, a light webbed iron block, non rebuildable. The little Yanmar develops a whopping 19 HP at 2100 rpm. Gravity feed fuel system, simple injection pumps and nozzles, and factory hydraulics with a 3 point hitch. I bought the Yanmar used at a sealed-bid auction in 1991, and have been using it ever since. Other than routine maintenance, it just runs. No electronics to get out of whack, no complex diesel exhaust treatment system. It's a basic little tractor and plenty for our needs. I plow our driveway with it in winter, keep a boom pole on it to load/unload my engine driven welders from my pickup, and use it for other odd jobs. It looks like a tractor ought to look. The new breeds of Japanese and Indian subcompact and compact tractors went for 'sports car styling' and look bizarre, at least to my eye.