Given a travel related situation, and given a specific question about the situation, summarize the question into a title

[Q]: On a flight with Air Transat, passengers were informed that for use in the in-flight entertainment system, only earbud style earphones were permitted.

I ignored this and used my on-ear style earphones (I hate earbud style earphones), and the cabin crew did not tell me to take them off. I could still clearly hear announcements, and in any case, those announcements could be transmitted through the audio of the in-flight entertainment system, so being unable to hear important ambient sounds does not seem a reasonable motivation.

Why would only earbud style earphones be permitted? Is this rule common and commonly enforced?

[A]: Why only earbud style earphones?

[Q]: How long time does it take to get through Immigration at Terminal B in Newark these days?

Arriving from Oslo, Norway, going to Ft. Lauderdale. I have 1h and 35min.

[A]: Immigration delay at Newark airport

[Q]: I've read the border between Thailand and Cambodia was difficult to cross for foreigners.

What's the best way to cross that border for foreigners ? Is taking a flight mandatory or is there other solutions ? And what would be the cost of the crossing ?

EDIT : I was hoping there was some preferred path to go from Vietnam to Cambodia. Let's say I want to leave from Bangkok to go to Siem reap.

What is safe for me ? Something that does not look like this thread

What is cheap ? Everything will be cheaper than what I'm use to. I want to know the cheapest path that is relatively safe. Crossing the border illegally is obviously not an option.

[A]:
What is the cheapest and safest way from Thailand to Cambodia?