why partition pruning doesn't work?

CREATE TABLE data(a text, vlozeno date) PARTITION BY RANGE(vlozeno);
CREATE TABLE data_2016 PARTITION OF data FOR VALUES FROM ('2016-01-01') TO ('2016-12-31');
CREATE TABLE data_2017 PARTITION OF data FOR VALUES FROM ('2017-01-01') TO ('2017-12-31');
CREATE TABLE data_other PARTITION OF DATA DEFAULT;

insert into data select 'ahoj', '2016-01-01'::date + (random() * 900)::int from generate_series(1,1000000);
analyze data;

postgres=# explain analyze select * from data where vlozeno > '2018-06-01';
┌──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                      QUERY PLAN                                                      │
╞══════════════════════════════════════════════════════════════════════════════════════════════════════════════════════╡
│ Append  (cost=0.00..3519.83 rows=20001 width=9) (actual time=0.042..27.750 rows=19428 loops=1)                       │
│   ->  Seq Scan on data_other  (cost=0.00..3419.83 rows=20001 width=9) (actual time=0.040..25.895 rows=19428 loops=1) │
│         Filter: (vlozeno > '2018-06-01'::date)                                                                       │
│         Rows Removed by Filter: 171518                                                                               │
│ Planning Time: 0.766 ms                                                                                              │
│ Execution Time: 28.718 ms                                                                                            │
└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
(6 rows)

postgres=# explain analyze select * from data where vlozeno > current_date;
┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                                             QUERY PLAN                                                              │
╞═════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════════╡
│ Gather  (cost=1000.00..17281.36 rows=20080 width=9) (actual time=0.749..95.389 rows=19428 loops=1)                                  │
│   Workers Planned: 2                                                                                                                │
│   Workers Launched: 2                                                                                                               │
│   ->  Parallel Append  (cost=0.00..14273.36 rows=8367 width=9) (actual time=59.141..89.458 rows=6476 loops=3)                       │
│         ->  Parallel Seq Scan on data_2016  (cost=0.00..5768.69 rows=24 width=9) (actual time=34.847..34.847 rows=0 loops=3)        │
│               Filter: (vlozeno > CURRENT_DATE)                                                                                      │
│               Rows Removed by Filter: 135119                                                                                        │
│         ->  Parallel Seq Scan on data_2017  (cost=0.00..5745.02 rows=23 width=9) (actual time=53.269..53.269 rows=0 loops=2)        │
│               Filter: (vlozeno > CURRENT_DATE)                                                                                      │
│               Rows Removed by Filter: 201848                                                                                        │
│         ->  Parallel Seq Scan on data_other  (cost=0.00..2717.82 rows=11765 width=9) (actual time=0.044..55.502 rows=19428 loops=1) │
│               Filter: (vlozeno > CURRENT_DATE)                                                                                      │
│               Rows Removed by Filter: 171518                                                                                        │
│ Planning Time: 0.677 ms                                                                                                             │
│ Execution Time: 98.349 ms                                                                                                           │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
(15 rows)