There would be avenues for disputing charges, including with national regulators, if you think your carrier makes bad judgment calls. However, companies could regularly (if temporarily) apply those surcharges in "exceptional circumstances" where customers in their home markets face price hikes or other "negative effects." Telecoms would have to show that free roaming was threatening their domestic pricing model.

If the European Parliament likes the approach and puts into effect ahead of a June 15th, 2017 target date, it could be helpful for EU residents who spend large stretches of time away from their homeland. However, the fuzziness of this roaming plan has its problems. Where do carriers draw the line for abuse? There's a risk that carriers will keep the threshold artificially low, guaranteeing that you'd face surcharges if you use your phone even slightly more than usual (say, to share vacation photos). The EU may need to carefully define its definition of misuse if it wants to avoid a public outcry.