It was all marketing and I'm probably gonna' piss some people off.
In the mid '70s Canon introduced the AE1--for automatic exposure 1. They advertised the hell out of it in every media. Canon was singularly responsible for the 35mm boom.
The US was a huge untapped market for (relatively) high dollar, high quality 35mm product and everybody wanted a piece of it. The top 5, in order of volume, were: Canon, Minolta, Nikon, Pentax and Olympus.
Canon (F1), Nikon (F) and Olympus (OM1) offered honest to God professional photojournalist tools. Pentax was slow to move to the larger bayonet K lens mount from the (world standard) 42mm thread mount. As a result they couldn't incorporate auto aperture control and wide open metering, thus the former leader in 35mm SLR (Spotmatic) was left in the catch up position. Leica was, and still is, priced out of the market for all but the most high-end pros and people with more money than good sense. Minolta built copiers and got into 35mm for the profit. Then there were a host of "just as good as but cheaper" entries none of which really affected the market because price was the driver over quality, innovation and marketing.
The "big five" all introduced entry level consumer oriented products to compete in the low cost SLR market. They were little more than point-n-shoot with detachable lenses. We referred to them as plastic fantastics. I think 90% of these cameras ever had a second lens added.
Competition for market share was intense, it made the current cellphone market look like just a bunch friends. Enter the SPIFF. SPIFFs are an additional commission on "preferred" products. As I recall Minolta started it with a $5.00 SPIFF paid directly to the counter sales person for every warranty card turned in. Nikon and Pentax followed suit with Cannon preferring to advertise and drive brand awareness until they couldn't compete at the retail sales counter. Olympus steadfastly refused to buy sales at the retail counter and it cost me a LOT of money.
Mass marketing retailers began using SPIFFs to cut the overhead of salaries. Every skylight filter that cost .25 and sold for $10 earned a SPIFF of $1. Cameras were advertised at dealer cost and sales people were forced to sell add-ons to make up the profit. The average entry SLR sold for $199 but the final sale was close to $400, all the accessories sold at 4-6x cost. The worst was the "extended warranty", then as now it is nothing short of fraud.
Four of the top five manufacturers and all of the "just as good as" brands were bribing sales people to sell their product. Olympus refused to do so. I almost came to blows with a Barry's Camera sales person who came to my counter, took my product to a SPIFF manufacturer and proceeded to tell outright lies about my product to close the sale.
Unfortunately every retail sales encounter has devolved to this kind of marketing.
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