OK, what am I missing here?  Laptop, linux-next kernel from last week.
And we'll skip the food fight about whether fq_codel makes sense for
end nodes - this is a different issue..

I've set fq_codel as the default qdisc

[/proc/sys/net] cat core/default_qdisc
fq_codel

but it's not being used?

[/proc/sys/net] tc -s qdisc show
qdisc noqueue 0: dev lo root refcnt 2
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
qdisc pfifo_fast 0: dev eth0 root refcnt 2 bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
qdisc noqueue 0: dev wlan0 root refcnt 2
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0

But if I give it a kick in the head...

[/proc/sys/net] tc qdisc add dev wlan0 root fq_codel
[/proc/sys/net] tc -s qdisc show dev wlan0
qdisc fq_codel 8001: root refcnt 2 limit 10240p flows 1024 quantum 1514 target 5ms interval 100ms memory_limit 32Mb ecn drop_batch 64
 Sent 812 bytes 12 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
  maxpacket 0 drop_overlimit 0 new_flow_count 0 ecn_mark 0
  new_flows_len 0 old_flows_len 0

(Admittedly, my first guess is "systemd is probably being its fascist self
and setting it to what *it* thinks things should be like"... :)