Others have commented about eminent domain in the US. I can add that for the European countries I know, compulsory purchase/expropriation does not rely on the consent of the previous owners at all. So the 70% threshold would not be typical, it's really 0%.
That's not to say the state can do anything or that projects cannot be delayed. The details vary but there are usually a couple of principles limiting expropriation to specific purposes (for the ‘public good’ or some similar notion) and requiring a fair compensation, under the control of the courts. Securing the landowners' approval can therefore be useful to avoid lengthy court proceedings but ultimately the decision rests with an ostensibly neutral third party (the court system) rather than with the state or the owners themselves.
If someone wants to try to derail a project, they would need to argue that they haven't been compensated properly or perhaps that the purpose is blatantly illegal, that the damage they would suffer is disproportionately high, etc. and not merely that they do not consent to the expropriation because that's not relevant, legally speaking.
On a more political level, you can observe that this system does not always succeed in regulating this process peacefully. The scale might be smaller than in India (European countries are small and nobody builds big dams anymore!) but there are several recent infrastructure projects that met with significant and at times (relatively) violent resistance (I am thinking about Stuttgart 21 in Germany or Notre-Dame-des-Landes airport in France).