Those questions are of interest but are not an adequate response to the well known FACT that fugative slaves were one of the Slavers' greatest problems. In addition, in the state of Virginia freed slaves were NOT ALLOWED to stay there by state law. Besides comparing a free man's actions to those of a slave is silly.
Actually that law was extremely nuanced, had certain exemptions to it, did not affect free blacks already living there, and permitted a substantial grace period (a year IIRC). Compare that to Illinois where virtually ANY black who entered the state's borders and remained for more than about a week was automatically a criminal who could then be sold at public auction into indentured servitude. Before the war Maryland seems to have been the best place for free blacks to live as indicated by the fact that it had the largest free black population.
Such laws were common in the South.
The salient point, as our friend has pointed out, is that free States also had such laws, which would seem to be absurd on the face of it.
The fact is that such laws weren't about slavery so much as race. Slavery was the background, but race was on the point of the legislation.
Regarding your purportedly "well known" but undocumented "FACT" there is the much better known and very well documented fact of the CENSUS of 1860. The TOTAL Black population in the FREE states was 221,224. If runaway slaves were as great a problem as you purport, WHERE WERE THEY????
The FREE states had a TOTAL FREE BLACK population of 221,224 as of 1860.
CA 4,086 CT 8,627 IL 7,628 IN 11,428 IA 1,069 ME 1,327 MA 9,602 MI 6,799 MN 259 NH 494 NJ 25,318 NY 45,005 OH 36,673 OR 128 PA 56,949 RI 3,952 VT 709 WI 1,171 TL 221,224