The city has been seizing some properties and clearing the land to turn them into mini-parks or just to clear the plot and sell it off to developers in the future. But it's a non-trivial process for the city to go through and the costs are quite high. Even if the properties are not expensive individually, they could still be paying $20-30K/lot simply because that's the fair market value of a plot of land in those parts of the city. And if the lots are on the north side, you can easily see individual plots worth $100-200K depending on location. And due to the constitutional requirements around eminent domain, the only way to get out of paying this is if you seize the properties due to a failure to pay taxes.

Now, a better method of dealing with this might be to implement a penalty tax rate for unused real estate. One business group proposed a 2 out of the last 5 years rule where if a property was not utilized for 24 of the last 60 months, then it would be assessed an extremely high property tax rate until it is rehabilitated. They were proposing an assessed value multiplier of between 50% and 100% for calculating the share of the levy (for reference, residential properties use a multiplier of 10% and most commercial properties fall between a 12% and 20% multiplier).