The Delta City problem

ROBOCOP

In the beginning of RoboCop, the Old Man says that Delta City will begin construction in 6 months.
Much later in the movie, when Robocop is on his way to Jones' office, he enters Delta City under construction  - it's even confirmed to be Delta City in the special features from the 20th Anniversary edition by a matte painter who did the shot, Rocco Gioffre, confirming it's Delta City. It can be found on the Special Effects section of the DVD: "There's a wide shot of Delta City when Robocop's car is driving away from camera" and the above mentioned shot is shown. 

Take a closer look, there's a construction going on on the left and that at least 3 skyscrapers are still under construction. Gioffre isn't the only source confirming that this is indeed Delta City. 1987's Cinefantastique magazine confirms it as well

Now the problems begin - the next day Jones tells Clarence that Delta City begins construction in 2 months...oversight?

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ROBOCOP 2

Now lets move on to RoboCop 2. Even if we ignore that we've already seen Delta City being raised and if we only take the 2 months comment, then it seems like the construction was postponed for some reason. The movie takes place about a year after the original, and Delta City is still just a blueprint. RoboCop II is built to clean up the city from crime for the construction, and OCP still needed to foreclose and take the city private in order to greenlight the project 

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ROBOCOP 3

Now RoboCop 3. Its hard to tell how much time have passed, but we have different hairdo on Lewis again and Reed and Johnson visibly aged. That, and now we see OCP in serious trouble and on its last knees, and partially owned by Kanemitsu, and with new CEO and with Johnson as Vice President. All that must've taken a lot of time. And yet, Delta City is still not ready and rehabs are forcing people out of their homes in order for demolition to begin, and here's when things get even more confusing - so the whole point of rehabs is to make Cadillac Heights clear for demolition...well, didn't they start the demolition already within the first few minutes of the movie?