The most specific term used seems to be "issue bundling":
The analysis isolates three reasons why the forces of electoral competition may not, by themselves,
be sufficient to produce congruence between citizen preferences and policy outcomes on
both issues. These are (i) when there are divergences between elite and popular opinion on an
issue and that issue is not salient in the election; (ii) when there is a group of voters who hold a
minority view on an issue but vote as single issue voters; and (iii) when a minority view is supported
by an organized interest group that provides campaign contributions to candidates sharing
its position. The logic of each of these arguments rests on issue bundling — the fact that citizens
have only one vote to cast for a representative who must decide on a bundle of issues. This echoes
a familiar theme in political science.
It's been often discussed as one of the problems that direct democracy attempts to solve:
The theory of direct democracy revolves around three ideas: principal-agent
problems, asymmetric information and issue bundling. [...]
Legislatures often bundle issues together in omnibus bills that are voted on as
a package. This “logrolling” allows legislators to trade votes with each other and
gain approval of their top priorities by giving ground on issues they consider of
secondary importance. Initiatives and referendums give citizens a way to unbundle
specific issues. In terms of efficiency, unbundling can be good or bad depending on whether
logrolling itself is efficient. [...]
Candidates are also bundles—they take positions on multiple issues—and
voters must accept or reject them as packages. By stripping out individual issues,
direct democracy reduces the number of issues on which candidates take positions,
which theory suggests improves the representation process. When candidates run
on fewer issues, citizens can send stronger messages at the voting booth and are less
likely to have to support a candidate who is right on some issues but wrong on
others.
It has also been studied in terms of this bundling occuring at party level:
We present results of a U.S. survey experiment in which candidate platforms are held fixed and
only the number of candidates is altered across treatment conditions. We contrast conditions with and
without issue bundling, and discover that in a hypothetical four-party system, the correlation between
policy preferences and vote choice increases for both the economic and moral dimensions, but far more
for the latter. We interpret this as evidence that policy bundling asymmetrically suppresses the moral
values dimension of conflict.
And as you may guess from the above, issue bundling may be a problem even in the absence of representatives (or parties), e.g. having to yea or nay a single large legislative package (like a constitution) in a referendum:
Bundling is generally viewed with some skepticism in the public choice literature. By
aggregating several issues together, voters may, in some circumstances, choose a bundle that does not
reflect their true preferences. Of course, if there were no transactions costs to bargaining, it would not
matter whether issues were presented individually or as a bundle. In the real world, however, the
agenda setter may determine the outcome by presenting issues as a bundle. Bundling might allow
interest groups to piggy back on generally-approved principles by sneaking in unnecessary policies. This
might take the form of logrolling (when two policies supported by different minorities are aggregated to
generate majority support), or a rider (in which a policy supported by the majority is bundled with one
that would only generate minority support).
When voters are presented with a choice is as momentous as the adoption of the constitution,
in which the prospective costs of reaching no agreement might be overwhelming, they may accept a
certain amount of interest group benefits in the bargain. Bundling at the outset of the constitution
could produce a document full of special interests and logrolling. In contrast, the more incremental
change of a constitutional amendment is rarely as momentous. The cost of failure is less high. Further,
because amendments are focused on fewer subjects, we might expect them to produce a more accurate
reflection of voter preferences than would an up or down vote on the initial bundle of compromises. If
a single subject rule is in place, it might restrict interest group activity, and eliminate Condorcet losers
(Levmore 2005). From this point of view, we might favor amendment over constitution-making as less
susceptible to rent-seeking in some circumstances.
Broader terms that may encompass other things are "limited choice" or "constrained democracy", although these are not strictly about individuals, e.g. they can refer to having to choose among a given set of parties too. These latter notions may even apply to direct democracy, e.g. to referenda.
