The charge neutrality point (CNP) of graphene nanoribbons (GNRs) patterned by oxygen plasma etching moves towards zero as the ribbon narrows and, on 300 nm SiO2, changes sign below a crossover width of ~ 50 nm: an observation previously attributed to n-type edges surrounding a p-type bulk. We test this edge-doping hypothesis in three ways. First, finite element modelling of complete GNR transistors with uniform doping shows that fringing of the gate field at the edges reproduces the trend of the measured CNP with width down to ~ 50nm without any edge doping, while producing a bias-dependent inversion of the carrier type at the edges that mimics n-type edges in scanned-probe measurements. Second, fitting the CNP of ribbons on 90 nm and 300 nm SiO2 with the gate capacitance of a finite strip, which fixes the electrostatic contribution with no adjustable parameter other than the bulk doping, shows that fringing accounts for most of the width dependence and isolates the remainder as an edge charge. This is acceptor-like (0.24 e/nm per edge) in the present ribbons, which therefore have no n-type edges, and donor-like but small in devices on 300 nm SiO2; no single edge-charge, field-coupled or contact-doping mechanism describes both. Third, scanning gate microscopy finds no edge contrast of the sign expected for n-type edges. The width dependence of the CNP is therefore predominantly electrostatic, and n-type edges are not an intrinsic consequence of oxygen-plasma etching. A design map shows that fringing dominates the width dependence whenever the gate dielectric is thicker than 30-50 nm, whereas in scaled high-K transistors, edge charge dominates and would shift the threshold voltage of a 10 nm ribbon by ~ 0.1-0.15 V. Fitting the CNP versus width with the strip capacitance provides a simple test for edge doping in any gated two-dimensional nanostructure