It’s funny - Tesla initially offered a very well priced Enhanced Autopilot with TACC, lane keep assist, NOAP with or without lane change assist, summon, and assisted park - for $5000 at the time of purchase. Even then, a FSD pre-purchase (I think it was $6000) was available for additional money; except it would come with nothing other than a receipt for the future. If you didn’t buy any of these upgrades, your Tesla would come with basic cruise control.
As the year went by, it seems like Tesla slowly removed the bottom four features from the Enhanced Autopilot and put them under FSD to be able to offer something for those who are pre-purchasing it, and reduced the price of Autopilot pre-purchase (now only consisting of TACC and lane keep assist) from $5000 to $3000. FSD still steadily showed $6000. And then the final act was to kill Autopilot package altogether and make it a standard feature and reduce the price of the car slightly to make FSD even more lucrative
The above is largely incorrect.
Tesla originally (and by that I mean 2016 when they killed AP1 and introduced AP2) sold EAP for $5000 (and it includes all current, active, AP-related features)
They also offered FSD (promise of future features- specifically flat out Level 5 driving) for $3000 more (not 6 as you suggest)
(both prices pre-purchase, post purchase were a bit higher.)
Nothing there really changed at all for 2 years after that. $8000 all-in for everything pre-purchase, more after.
Then roughly late 2018 they kept EAP as is, but took FSD "off menu" meaning you had to specifically ask for it to get it, it was no longer an option in the online configurator, but you COULD still get it- same price even.
Then end of Feb 2019 they made the one major change to the lineup they've made at all (as opposed to the "slow removal of features" you suggest)....
EAP no longer was sold, nor was the old "we promise you level 5 FSD"...which, to remind you, cost $8000 total pre-purchase.
Instead you could buy "basic" autopilot which was just TACC and auto-steer in a single lane...for $3000... and "new" FSD, which gave you all the other existing features that used to come in EAP... plus the promise of... a MUCH more limited set of future features... specifically enhanced summon (which EAP owners will get too)... and stoplight/stopsign recognition and local drive on nav (which they won't) by end of this year... and then "more" later.
Notice this was still $8000 total, and again it cost more post-purchase than that.
They've played around with pricing a little since then...(including the ill-fated, later-admitted-mistake, of reducing FSD for late-adopters that only lasted a week or two) and eventually they just made "basic" AP free on most trims, while raising (not lowering as you suggest) the price of the cars- essentially making it a "forced" option on everything except the off-menu cars (LR RWD and SR at the time)
In any event it leaves an interesting dichotomy... Pre-March-2019 buyers who went all in have so far gotten 0 extra functionality for their roughly $8000.... but they are promised real L5 driving for their money. Post-March-2019 buyers who did the same immediately got significant functionality (auto lane change, nav on AP, auto-park, summon, etc) but are promised a much narrowed future feature set... (Tesla still kind of IMPLIES they'll get some sort of L5, but it's not in the actual FSD description like it used to be pre-March-19 change)