Aren’t they already doing that?
I mean, Columbus has gone out and annexed all of Franklin County and then some.
Columbus had the advantage of being able to blackmail unincorporated areas of the county with denial of water service if they didn't allow themselves to be "annexed". I believe that has pretty much come to an end in Ohio with their more recent annexation laws.
Unfortunately, Tennessee (where I now reside) still hasn't learned the lessons of the overemphasis on annexing. Chattanooga, under RINO Mayor Littlefield, has been trying to go on an annexing rempage, gobbling up hunks of unincorporated Hamilton County for quite a while now. The state needs some new annexation laws badly to keep the greedy cities from gobbling up more land and forcing people to pay double and triple their present property tax rates for NO INCREASE IN SERVICES!
Columbus is the exception. Cincinnati, Dayton and Cleveland are all surrounded by suburbs. I don't know about Akron, Canton, Youngstown or Toledo.
Dayton was notorious for annexing any businesses in nearby unincorporated areas because the entire township had no say - only the city and the people living in the area being annexed. The last couple townships finally incorporated to end that.
Where I live, the city has been charging an occupation tax to people who live in the suburbs, but work in the city.
Ohio is the opposite. Where you work gets the first cut and where you live usually gives you a credit for taxes paid where you work - but a few cities have started to limit that credit so you can pay for both. Currently I pay 1.5% where I work and an extra 0.75% (2.25% city rate - 1.5% credit) where I live. Fortunately my city credits the full amount paid elsewhere so I don't have to pay even more.