Point of order: the US is far from unique in having a written constitution. Most developed countries have a written constitution that, among other things, guarantees (on paper) basic rights to their citizens. The only exception is the UK, which does not have a single written constitutional document.
As you say, the commitment to basic democratic rights is considerably stronger in other western countries than in the US. The kind of abuses the Republican party habitually conducts with the aim of disenfranchising Democratic voters would not be tolerated elsewhere; this is reflected by the fact that the US constitution only explicitly prohibits certain forms of electoral discrimination (i.e. it's a blacklist policy) but does not explicitly grant a right to vote.
As you say, the commitment to basic democratic rights is considerably stronger in other western countries than in the US. The kind of abuses the Republican party habitually conducts with the aim of disenfranchising Democratic voters would not be tolerated elsewhere; this is reflected by the fact that the US constitution only explicitly prohibits certain forms of electoral discrimination (i.e. it's a blacklist policy) but does not explicitly grant a right to vote.