Yes, eminent domain WAS an issue, but most of the early non Common Carrier short lines (mostly Tap Lines and Steel Plant lines) took their case to the ICC INSISTING that they be made common carriers for "their" division of interline revenues. Some of these lines make the RGS look like the AT&SF.
Prior to the Supreme Court Decision giving these types of railroads the right to call themselves common carriers, the ICC did a very extensive study of these industry lines, like the Steelton & Highspire, for example, which was a wholly owned subsidiary of Bethlehem Steel.
Their claim to common carriage was tenuous, however, and before the Supreme Court Ruling, many were rejected by the ICC on the grounds that one car a year for an off-property customer does not a Common Carrier make.
The published reports of the ICC carries a very extensive overview of these cases up until about 1916 when the ruling came down from the bench. Then the Short and Tap Line cases disappear until valuation and reparation time.
Whether eminent domain, easements, or divisions, It was still about money, pure and simple.
I wish to protest that part that the Interurbans did not issue waybills. They most certainly did, as a waybill is as much a bill as the credit card bills that you get in the mail, and was their source of freight revenue.
Rick